| introduction of polyphosphate as a novel phosphate pool in the chloroplast of transgenic potato plants modifies carbohydrate partitioning. | potato plants (solanum tuberosum l., cv. désirée) were transformed with the polyphosphate kinase gene from escherichia coli fused to the leader sequence of the ferredoxin oxidoreductase gene (fnr) from spinacea oleracea under the control of the leaf specific st-ls1 promoter to introduce a novel phosphate pool in the chloroplasts of green tissues. transgenic plants (cpppk) in tissue culture developed necrotic lesions in older leaves and showed earlier leaf senescence while greenhouse plants showe ... | 2000 | 10674215 |
| highly purified thermo-stable oxygen-evolving photosystem ii core complex from the thermophilic cyanobacterium synechococcus elongatus having his-tagged cp43. | the carboxyl terminus of the cp43 subunit of photosystem ii (psii) in the thermophilic cyanobacterium, synechococcus elongatus, was genetically tagged with six consecutive histidine residues to create a metal binding site on the psii supramolecular complex. the histidine-tagging enabled rapid isolation of an intact cyanobacterial psii core complex from dodecyl maltoside-solubilized thylakoids by a simple one-step ni(2+)-affinity column chromatography. the isolated core complex was in a dimeric f ... | 1999 | 10682344 |
| foods contributing to absolute intake and variance in intake of selected vitamins, minerals and dietary fiber in middle-aged japanese. | using 351 one-day weighted diet records, we selected foods providing vitamins, minerals and dietary fiber according to contribution analysis (ca) and multiple regression analysis (mra). vitamin c was supplied by various vegetables and fruits, and carotene was specifically derived from green-yellow vegetables based on mra as well as ca. vitamin a was provided by green-yellow vegetables, fruits, chicken egg and milk (whole) according to ca; whereas chicken liver and pork liver were major sources a ... | 1999 | 10683805 |
| ras protein of the slime mold physarum polycephalum is farnesylated in vitro. | physarum ppras1 protein was efficiently prenylated by prenyltransferases of spinach. surprisingly in spite of the c-terminal sequence (clll) specific for geranylgeranylation the protein was preferentially farnesylated. consequences of this observation are discussed. | 1999 | 10698285 |
| the effect of rumen adaptation to oxalic acid on selection of oxalic-acid-rich plants by goats. | rumen microbial degradation is an important route for detoxification of secondary plant compounds encountered in the diets of free-grazing ruminants. exposure to diets containing particular secondary plant compounds can lead to increased rates of secondary compound degradation in the rumen. an experiment was conducted to determine whether rumen adaptation to oxalic acid would influence the diet selection of goats offered choices between plant species differing in their oxalic acid content. twelv ... | 2000 | 10703465 |
| cryptosporidium parvum appears to lack a plastid genome. | surprisingly, unlike most apicomplexa, cryptosporidium parvum appears to lack a plastid genome. primers based upon the highly conserved plastid small- or large-subunit rrna (ssu/lsu rrna) and the tufa-trnaphe genes of other members of the phylum apicomplexa failed to amplify products from intracellular stages of c. parvum, whereas products were obtained from the plastid-containing apicomplexans eimeria bovis and toxoplasma gondii, as well as the plants allium stellatum and spinacia oleracea. dot ... | 2000 | 10708370 |
| inhibitory copper binding site on the spinach cytochrome b6f complex: implications for qo site catalysis. | the isolated cytochrome (cyt) b(6)f complex from spinach is inhibited by cu(2+) with a k(d) of about 1 microm at ph 7.6 in the presence of 1.6 microm decyl-plastoquinol (c(10)-pqh(2)) as a substrate. inhibition was competitive with respect to c(10)-pqh(2) but noncompetitive with respect to horse heart cyt c or plastocyanin (pc). inhibition was also ph-sensitive, with an apparent pk at about 7, above which inhibition was stronger, suggesting that binding occurred at or near a protonatable amino a ... | 2000 | 10727220 |
| molecular weight determination of membrane proteins by sedimentation equilibrium at the sucrose or nycodenz-adjusted density of the hydrated detergent micelle. | the determination of the molecular weight of a membrane protein by sedimentation equilibrium is complicated by the fact that these proteins interact with detergents and form complexes of unknown density. these effects become marginal when running sedimentation equilibrium at gravitational transparency, i.e., at the density corresponding to that of the hydrated detergent micelles. dodecyl-maltoside and octyl-glucoside are commonly used for dissolving membrane proteins. the density of micelles the ... | 2000 | 10727607 |
| molecular characterization and physiological role of ascorbate peroxidase from halotolerant chlamydomonas sp. w80 strain. | a cdna clone encoding an ascorbate peroxidase was isolated from the cdna library from halotolerant chlamydomonas w80 by a simple screening method based on the bacterial expression system. the cdna clone contained an open reading frame encoding a mature protein of 282 amino acids with a calculated molecular mass of 30,031 da, preceded by the chloroplast transit peptide consisting of 37 amino acids. in fact, ascorbate peroxidase was localized in the chloroplasts of chlamydomonas w80 cells; the act ... | 2000 | 10729193 |
| compartmentation of atp:citrate lyase in plants. | extracts prepared from young leaves of pea (pisum sativum), tobacco (nicotiana tabacum), rape (brassica napus), and spinach (spinacia oleracea) all contained atp:citrate lyase (acl) activity, which was most active in rape leaflets (130 nmol min(-1) g fresh weight). in rape and spinach, acl activity was predominantly localized in the plastids (between about 78% and 90% of the total activity), whereas in pea and tobacco, distribution was mainly cytosolic (about 85% and 78%, respectively, of the to ... | 2000 | 10759519 |
| an endogenous proteinacious inhibitor in porcine liver for s-adenosyl-l-methionine dependent methylation reactions: identification as oligosaccharide-linked acyl carrier protein. | a proteinacious inhibitor of s-adenosyl-l-methionine (adomet)-dependent transmethylation reactions was purified to homogeneity from porcine liver by size exclusion chromatography and fplc. the molecular weight of the inhibitor was 12,222 da. a 7400 da polypeptide fragment of the purified inhibitor was sequenced by matrix-associated laser desorption ionization; time-of-flight ms, and was found to be identical with the known sequence of spinach acyl carrier protein (acp). although the remainder of ... | 2000 | 10762071 |
| atpase activity of a highly stable alpha(3)beta(3)gamma subcomplex of thermophilic f(1) can be regulated by the introduced regulatory region of gamma subunit of chloroplast f(1). | a mutant f(1)-atpase alpha(3)beta(3)gamma subcomplex from the thermophilic bacillus ps3 was constructed, in which 111 amino acid residues (val(92) to phe(202)) from the central region of the gamma subunit were replaced by the 148 amino acid residues of the homologous region from spinach chloroplast f(1)-atpase gamma subunit, including the regulatory stretch, and were designated as alpha(3)beta(3)gamma((tct)) (thermophilic-chloroplast-thermophilic). by the insertion of this regulatory region into ... | 2000 | 10777572 |
| suppressor mutations in the chloroplast-encoded large subunit improve the thermal stability of wild-type ribulose-1,5-bisphosphate carboxylase/oxygenase. | a temperature-conditional, photosynthesis-deficient mutant of the green alga chlamydomonas reinhardtii, previously recovered by genetic screening, results from a leucine 290 to phenylalanine (l290f) substitution in the chloroplast-encoded large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco, ec ). rubisco purified from mutant cells grown at 25 degrees c has a reduction in co(2)/o(2) specificity and is inactivated at lower temperatures than those that inactivate the wild-type ... | 2000 | 10779514 |
| chloroplast ribonuclease p does not utilize the ribozyme-type pre-trna cleavage mechanism. | the transfer rna 5' maturation enzyme rnase p has been characterized in bacteria, archaea, and eukarya. the purified enzyme from all three kingdoms is a ribonucleoprotein containing an essential rna subunit; indeed, the rna subunit of bacterial rnase p rna is the sole catalytic component. in contrast, the rnase p activity isolated from spinach chloroplasts lacks an rna component and appears to function as a catalytic protein. nonetheless, the chloroplast enzyme recognizes a pre-trna substrate fo ... | 2000 | 10786845 |
| polyadenylation of three classes of chloroplast rna in chlamydomonas reinhadtii. | three classes of rna, represented by atpb and petd mrnas, arg and glu trnas, and 5s rrna, were found to exist in polyadenylated form in chlamydomonas reinhardtii chloroplasts. sequence analysis of cdna clones derived from reverse transcriptase-polymerase chain reaction protocols used to select polyadenylated rnas revealed that, at least for the mrnas and trnas, there are three apparent types of polyadenylation. in the first case, the poly(a) tail is added at or near the mature 3' end, even when ... | 2000 | 10786850 |
| mechanism of activation of the chloroplast atp synthase. a kinetic study of the thiol modulation of isolated atpase and membrane-bound atp synthase from spinach by eschericia coli thioredoxin. | the mechanism of thiol modulation of the chloroplast atp synthase by escherichia coli thioredoxin was investigated in the isolated atpase subcomplex and in the atp synthase complex reconstituted in bacteriorhodopsin proteoliposomes. thiol modulation was resolved kinetically by continuously monitoring atp hydrolysis by the isolated subcomplex and atp synthesis by proteoliposomes. the binding rate constant of reduced thioredoxin to the oxidized atpase subcomplex devoid of its epsilon subunit could ... | 2000 | 10788430 |
| effect of fruits, vegetables, or vitamin e--rich diet on vitamins e and c distribution in peripheral and brain tissues: implications for brain function. | age-related neurodegenerative conditions are the principal cause of declining cognitive and motor function during aging. evidence support that fruits and vegetables containing generous amounts of antioxidant nutrients are important for neurological function. we investigated the effect of diets enriched with fruits or vegetables but low in vitamin e and a diet high in vitamin e on the distribution of vitamins c and e in the brain and dopamine release of fischer 344 rat model, over an 8-month peri ... | 2000 | 10795718 |
| three-dimensional structure of chlamydomonas reinhardtii and synechococcus elongatus photosystem ii complexes allows for comparison of their oxygen-evolving complex organization. | electron microscopy and single-particle analyses have been carried out on negatively stained photosystem ii (psii) complexes isolated from the green alga chlamydomonas reinhardtii and the thermophilic cyanobacterium synechococcus elongatus. the analyses have yielded three-dimensional structures at 30-a resolution. biochemical analysis of the c. reinhardtii particle suggested it to be very similar to the light-harvesting complex ii (lhcii).psii supercomplex of spinach, a conclusion borne out by i ... | 2000 | 10807922 |
| identification, purification, and molecular cloning of a putative plastidic glucose translocator. | during photosynthesis, part of the fixed carbon is directed into the synthesis of transitory starch, which serves as an intermediate carbon storage facility in chloroplasts. this transitory starch is mobilized during the night. increasing evidence indicates that the main route of starch breakdown proceeds by way of hydrolytic enzymes and results in glucose formation. this pathway requires a glucose translocator to mediate the export of glucose from the chloroplasts. we have reexamined the kineti ... | 2000 | 10810150 |
| antioxidant-rich diets improve cerebellar physiology and motor learning in aged rats. | the free radical theory of aging predicts that reactive oxygen species are involved in the decline in function associated with aging. the present paper reports that diets supplemented with either spinach, strawberries or blueberries, nutritional sources of antioxidants, reverse age-induced declines in beta-adrenergic receptor function in cerebellar purkinje neurons measured using electrophysiological techniques. in addition the spinach diet improved learning on a runway motor task, previously sh ... | 2000 | 10825496 |
| effects of spinach powder fat-soluble extract on proliferation of human gastric adenocarcinoma cells. | four kinds of assays were used to study the effect of a fat-soluble extract of spinach powder (spfe) on the proliferation of human gastric adenocarcinoma cell line (sgc-7901) in vitro. these studies included: (i) cell growth assay, (ii) colony forming assay, (iii) mtt colorimetric assay, and (iv) 3h-tdr incorporation assay. the concentrations of spfe expressed as the level of beta-carotene in the medium were 2 x 10(-8), 2 x 10(-7) and 2 x 10(-6) mol/l beta-carotene in assay (i)-(iii), but 4 x 10 ... | 1999 | 10840580 |
| modulation of 14-3-3 protein interactions with target polypeptides by physical and metabolic effectors. | the proteins commonly referred to as 14-3-3s have recently come to prominence in the study of protein:protein interactions, having been shown to act as allosteric or steric regulators and possibly scaffolds. the binding of 14-3-3 proteins to the regulatory phosphorylation site of nitrate reductase (nr) was studied in real-time by surface plasmon resonance, using primarily an immobilized synthetic phosphopeptide based on spinach nr-ser543. both plant and yeast 14-3-3 proteins were shown to bind t ... | 2000 | 10845467 |
| isolation and characterization of cdnas encoding ribosome inactivating protein from dianthus sinensis l. | to isolate a ribosome inactivating protein (rip) gene, six plant species were surveyed for antiviral activity. crude proteins extracted from these plants were tested for the antiviral activity against tobacco mosaic virus (tmv) in nicotiana glutinosa. all the plants, spinacia oleracea, amaranthus lividus, dianthus superbus, dianthus sinensis and celosia cristata, with an exception of oenanthe stolonifera, presented 70-90% inhibition of viral infectivity. in an attempt to search for the rip gene ... | 2000 | 10850653 |
| extra-ribosomal function(s) of the plastid ribosomal protein l4 in the expression of ribosomal components in spinach. | we have previously characterised the cdna corresponding to the nucleus-encoded, plastid ribosomal protein l4 from spinach. the l4 protein belongs to the group of ribosomal proteins for which extra-ribosomal functions have been demonstrated in prokaryotes. in general, these functions are concerned with the expression of ribosomal components. in order to analyse whether the plastid l4 protein might also have (an) extra-ribosomal function(s) we have produced the plastid l4 protein as a thioredoxin ... | 2000 | 10852486 |
| activase region on chloroplast ribulose-1,5-bisphosphate carboxylase/oxygenase. nonconservative substitution in the large subunit alters species specificity of protein interaction. | in the active form of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco, ec ), a carbamate at lysine 201 binds mg(2+), which then interacts with the carboxylation transition state. rubisco activase facilitates this spontaneous carbamylation/metal-binding process by removing phosphorylated inhibitors from the rubisco active site. activase from solanaceae plants (e.g. tobacco) fails to activate rubisco from non-solanaceae plants (e.g. spinach and chlamydomonas reinhardtii), and non-solanace ... | 2000 | 10858441 |
| recombinant expression of molybdenum reductase fragments of plant nitrate reductase at high levels in pichia pastoris. | mo reductase (mor; formerly cytochrome c reductase) fragments of nadh:no(3) reductase (nr; ec1.6.6.1) were cytosolically expressed in pichia pastoris, a methylotrophic yeast, using spinach (spinacia oleracea) and corn (zea maize) cdnas. in fermenter cultures, spinach mor was expressed at 420 mg l(-1), corn mor at 32 mg l(-1), and corn mor plus with putative nr interface domain n terminus (mor+) at 17 mg l(-1). constitutively expressed mor+ was structurally stable while it was degraded when expre ... | 2000 | 10859204 |
| phytotoxic compounds from the new coprophilous fungus guanomyces polythrix. | bioactivity-directed fractionation of the fermentation broth and mycelium of the coprophilous fungus guanomyces polythrix led to the isolation of several phytotoxic compounds, including five new naphthopyranone derivatives (1-5). in addition, rubrofusarin b, emodin, citrinin, and 4-hydroxybenzoic acid methyl ester were obtained. the structures of the new compounds were established by spectral and chiroptical methods. the isolates caused significant inhibition of radicle growth of two weed seedli ... | 2000 | 10869195 |
| electron microscopy and single molecule averaging of subunit-deficient f1-atpases from escherichia coli and spinach chloroplasts. | the morphology of f1-atpases lacking one or more small subunits has been investigated by minimal-beam electron microscopy of close-packed monolayers of molecules. computer-based rotational analyses of single molecules were performed on reconstituted 3-subunit f1-atpase (-delta epsilon) from escherichia coli and both 3-subunit (-delta epsilon) and 4-subunit (-delta) f1-atpase from chloroplasts. optical diffraction measurements of close-packed arrays revealed maximal dimensions of 122 +/- 4 a and ... | 1983 | 10872338 |
| the plastid ribosomal proteins. identification of all the proteins in the 30 s subunit of an organelle ribosome (chloroplast). | identification of all the protein components of a plastid (chloroplast) ribosomal 30 s subunit has been achieved, using two-dimensional gel electropholesis, high performance liquid chromatography purification, n-terminal sequencing, polymerase chain reaction-based screening of cdna library, nucleotide sequencing, and mass spectrometry (electrospray ionization, matrix-assisted laser desorption/ionization time-of-flight, and reversed-phase hplc coupled with electrospray ionization mass spectrometr ... | 2000 | 10874039 |
| the plastid ribosomal proteins. identification of all the proteins in the 50 s subunit of an organelle ribosome (chloroplast). | we have completed identification of all the ribosomal proteins (rps) in spinach plastid (chloroplast) ribosomal 50 s subunit via a proteomic approach using two-dimensional electrophoresis, electroblotting/protein sequencing, high performance liquid chromatography purification, polymerase chain reaction-based screening of cdna library/nucleotide sequencing, and mass spectrometry (reversed-phase hplc coupled to electrospray ionization mass spectrometry and electrospray ionization mass spectrometry ... | 2000 | 10874046 |
| beta-cyanoalanine synthase is a mitochondrial cysteine synthase-like protein in spinach and arabidopsis. | beta-cyano-alanine synthase (cas; ec 4.4.1.9) plays an important role in cyanide metabolism in plants. although the enzymatic activity of beta-cyano-ala synthase has been detected in a variety of plants, no cdna or gene has been identified so far. we hypothesized that the mitochondrial cysteine synthase (cs; ec 4.2.99. 8) isoform, bsas3, could actually be identical to cas in spinach (spinacia oleracea) and arabidopsis. an arabidopsis expressed sequence tag database was searched for putative bsas ... | 2000 | 10889265 |
| distribution of hammerhead and hammerhead-like rna motifs through the genbank. | hammerhead ribozymes previously were found in satellite rnas from plant viroids and in repetitive dna from certain species of newts and schistosomes. to determine if this catalytic rna motif has a wider distribution, we decided to scrutinize the genbank database for rnas that contain hammerhead or hammerhead-like motifs. the search shows a widespread distribution of this kind of rna motif in different sequences suggesting that they might have a more general role in rna biology. the frequency of ... | 2000 | 10899150 |
| structure and heterologous expression of a gene encoding fructose-6-phosphate,2-kinase/fructose-2,6-bisphosphatase from arabidopsis thaliana. | a full-length cdna clone encoding fructose-6-phosphate, 2-kinase/fructose-2,6-bisphosphatase from arabidopsis thaliana (atf2kp) was isolated. the encoded protein is composed of two different regions: (i) a 400 amino acid cooh-terminal region, covering the catalytic region of the protein which is homologous to enzymes from other eukaryotes. this region is highly conserved among plant species (88% identity to spinach f2kp). (ii) a 345 amino acid plant-specific nh(2)-terminal region, with 59% ident ... | 2000 | 10899575 |
| purification and characterization of 2-ethoxyphenol-induced cytochrome p450 from corynebacterium sp. strain ep1. | a soluble cytochrome p450 (p450ep1a) induced by 2-ethoxyphenol was purified to apparent homogeneity from corynebacterium sp. strain ep1. the p450ep1a showed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with a molecular weight of about 45 kda. the co-reduced difference spectra of p450ep1a had a soret maximum at 447.6 nm. the substrate difference spectra with 2-ethoxyphenol showed an absorption maximum at 394.0 nm. the purified p450ep1a degraded 2-ethoxyphenol in an a ... | 1999 | 10907420 |
| a survey of water activity and ph values in fresh pasta packed under modified atmosphere manufactured in argentina and uruguay. | the water activity (a(w)) and ph values of commercially available filled fresh pasta and gnocchi packed under modified atmosphere and manufactured in argentina and uruguay were examined. the retail survey included 58 samples (several brands) of filled pasta and 11 samples of gnocchi. fillings consisted of different combinations of cheese (various types), beef, ricotta, ham, chicken, and spinach. the survey revealed that the a(w) values of the 58 samples of filled pasta ranged from 0.916 to 0.973 ... | 2000 | 10914670 |
| chromatographic separation of a small subunit (psbw/psay) and its assignment to photosystem i reaction center. | by using a hydroxyapatite column, the five major photosystem i (psi) subunits (psaa,-b,-c,-d,-e) solubilized by sodium dodecyl sulfate (sds) were fractionated from a spinach psi reaction center preparation. another small (5-6 kda) polypeptide was also separated, and purified to homogeneity. mass spectroscopy yielded its molecular weight to be 5942 +/- 10. this polypeptide had an n-terminal sequence homologous to those of previously reported 5-kda subunits from spinach and wheat and a 6.1-kda sub ... | 2000 | 10924904 |
| effects of antioxidants apocynin and the natural water-soluble antioxidant from spinach on cellular damage induced by lipopolysaccaride in the rat. | oxidative damage plays a key role in septic shock induced by the endotoxin lipopolysaccaride (lps) by enhancing the formation of reactive oxygen species such as superoxide anion radicals, peroxides, and their secondary product, malondialdehyde, especially in the liver. in this study, histopathologic changes in several organs were compared among groups of male wistar rats that had been injected with lps following prophylactic pretreatment with either of 2 antioxidants, a group that had been injec ... | 2000 | 10930046 |
| the prophylactic effects of natural water-soluble antioxidant from spinach and apocynin in a rabbit model of lipopolysaccharide-induced endotoxemia. | radical-scavenging antioxidants, as part of the cellular defense system, function to inhibit the formation and propagation of free radicals and active oxygen species formation. in previous studies we demonstrated that endotoxin lipopolysaccharide (lps) promotes oxidative stress and associated pathological changes in a rat model and that use of selected antioxidants was effective in reducing lps-related lipid peroxidation product formation in the liver, as well as lps-related pathological changes ... | 2000 | 10930047 |
| genetic engineering of glycinebetaine synthesis in plants: current status and implications for enhancement of stress tolerance. | metabolic acclimation via the accumulation of compatible solutes is regarded as a basic strategy for the protection and survival of plants in extreme environments. certain plants accumulate significant amounts of glycinebetaine (betaine), a compatible quaternary amine, in response to high salinity, cold and drought. it is likely that betaine is involved in the protection of macrocomponents of plant cells, such as protein complexes and membranes, under stress conditions. genetic engineering of th ... | 2000 | 10938798 |
| the effects of ethylene, depressed oxygen and elevated carbon dioxide on antioxidant profiles of senescing spinach leaves. | it has been suggested that antioxidants play a role in regulating or modulating senescence dynamics of plant tissues. ethylene has been shown to promote early plant senescence while controlled atmospheres (ca; reduced o2 levels and elevated co2 levels) can delay its onset and/or severity. in order to examine the possible importance of various antioxidants in the regulation of senescence, detached spinach (spinacia oleracea l.) leaves were stored for 35 d at 10 degrees c in one of three different ... | 2000 | 10938820 |
| the location of the mobile electron carrier ferredoxin in vascular plant photosystem i. | in this study, we present the location of the ferredoxin-binding site in photosystem i from spinach. image analysis of negatively stained two-dimensional crystals indicates that the addition of ferredoxin and chemical cross-linkers do not significantly alter the unit cell parameters (for untreated photosystem i, a = 26.4 nm, b = 27.6 nm, and gamma = 90 degrees, space group p22(1)2(1) and for ferredoxin cross-linked photosystem i, a = 26.2 nm, b = 27.2 nm, and gamma = 90 degrees, space group p22( ... | 2000 | 10948201 |
| an a245t mutation conveys on cytochrome p450eryf the ability to oxidize alternative substrates. | cytochrome p450(eryf) (cyp107a1), which hydroxylates deoxyerythronolide b in erythromycin biosynthesis, lacks the otherwise highly conserved threonine that is thought to promote o-o bond scission. the role of this threonine is satisfied in p450(eryf) by a substrate hydroxyl group, making deoxyerythronolide b the only acceptable substrate. as shown here, replacement of ala(245) by a threonine enables the oxidation of alternative substrates using either h(2)o(2) or o(2)/spinach ferredoxin/ferredox ... | 2000 | 10956654 |
| moderate intervention with carotenoid-rich vegetable products reduces lipid peroxidation in men. | because of their antioxidant properties, carotenoids may have beneficial effects in preventing cancer and cardiovascular disease. however, in humans consuming carotenoid-rich vegetables, data concerning the antioxidant effects of carotenoids are rather scarce. a human intervention trial was conducted, therefore, to determine whether a moderately increased consumption of carotenoid-rich vegetables would influence the antioxidant status in 23 healthy men. this short-term feeding study lasted 8 wk ... | 2000 | 10958813 |
| effects of ph and energy supply on activity and amount of pyruvate formate-lyase in streptococcus bovis. | the enzyme system of pyruvate formate-lyase (pfl) in streptococcus bovis was investigated by isolating pfl and pfl-activating enzyme (pfl-ae) from s. bovis, flavodoxin from escherichia coli, and chloroplasts from spinach. in this study, the pfl and pfl-ae in s. bovis were found to be similar to those in e. coli, suggesting that the activating mechanisms are similar. the optimal ph of s. bovis pfl was 7.5, which is in contrast to the optimal ph of s. bovis lactate dehydrogenase, which is 5.5. the ... | 2000 | 10966389 |
| survival of salmonella hadar after washing disinfection of minimally processed spinach. | washing disinfection with chlorine is widely used to reduce the initial microbiological load during the preparation of minimally processed vegetables. the effects of initial concentration of chlorine, time and the liquid volume:produce weight ratio on the reduction of salmonella counts on inoculated spinach were evaluated using response surface methodology. initial chlorine concentration, time and the interaction between them had a significant effect on reduction of salmonella populations. howev ... | 2000 | 10972717 |
| identification and expression of a cdna for human glycolate oxidase. | the isolation and expression of a human liver cdna encoding a 43 kda protein with glycolate oxidase activity is described. the cdna (hao1) is 1128 bp and has a 1113 bp open reading frame. northern blot analysis detects a 1.8 kb mrna with expression restricted to the liver. the 370 amino acid protein has 89% sequence similarity to glycolate oxidase from mouse liver and 53% similarity to the spinach and arabidopsis enzymes. the protein has glycolate oxidase activity in vitro, as measured by the re ... | 2000 | 10978532 |
| molecular characterization and subcellular localization of protoporphyrinogen oxidase in spinach chloroplasts. | protoporphyrinogen oxidase (protox) is the last common enzyme in the biosynthesis of chlorophylls and heme. in plants, there are two isoenzymes of protox, one located in plastids and other in the mitochondria. we cloned the cdna of spinach (spinacia oleracea) plastidal protox and purified plastidal protox protein from spinach chloroplasts. sequence analysis of the cdna indicated that the plastid protox of spinach is composed of 562 amino acids containing the glycine-rich motif gxgxxg previously ... | 2000 | 10982422 |
| metabolic modeling identifies key constraints on an engineered glycine betaine synthesis pathway in tobacco. | previous work has shown that tobacco (nicotiana tabacum) plants engineered to express spinach choline monooxygenase in the chloroplast accumulate very little glycine betaine (glybet) unless supplied with choline (cho). we therefore used metabolic modeling in conjunction with [(14)c]cho labeling experiments and in vivo (31)p nmr analyses to define the constraints on glybet synthesis, and hence the processes likely to require further engineering. the [(14)c]cho doses used were large enough to mark ... | 2000 | 10982430 |
| effects of apocynin and natural antioxidant from spinach on inducible nitric oxide synthase and cyclooxygenase-2 induction in lipopolysaccharide-induced hepatic injury in rat. | the immunoreactivity of inducible nitric oxide synthase, and cyclooxygenase-2 was compared among groups of male wistar rats comprising those injected with lipopolysaccharide following pretreatment with either natural antioxidant from spinach or the antioxidant apocynin, with lipopolysaccharide without pretreatment with antioxidants, with each of the two antioxidants alone, and untreated controls. the grade of staining of both inducible nitric oxide synthase and cyclooxygenase-2 increased with th ... | 2000 | 10987211 |
| oxidative stress protection and vulnerability in aging: putative nutritional implications for intervention. | research indicates that vulnerability to oxidative stress (osv) may increase in aging, suggesting that age-related neurodegenerative diseases such as alzheimer's disease (ad) or vascular dementia (vad) may be superimposed upon a vulnerable neuronal environment. determinations in cell models have suggested that the enhanced osv may be the result of, (a) increases in membrane lipids, especially sphingomyelin and the sphingomyelin metabolite, sphingosine-1-phosphate, (b) decreases in glutathione, a ... | 2000 | 10996014 |
| a dicistronic construct for the expression of functional spinach chloroplast ferredoxin:thioredoxin reductase in escherichia coli. | ferredoxin:thioredoxin reductase (ftr) is a heterodimeric fe&z.sbnd;s containing disulfide reductase involved in the light-dependent activation of photosynthetic enzymes. we have designed a dicistronic construct for the heterologous expression of this nucleus encoded chloroplast protein in escherichia coli. the coding sequences for the two mature subunits have been inserted in tandem into the expression vector pet-3d. this dicistronic construct is correctly translated yielding soluble, perfectly ... | 2000 | 10996250 |
| the role of structural intersubunit microheterogeneity in the regulation of the activity in hysteresis of ribulose 1, 5-bisphosphate carboxylase/oxygenase. | many enzymes are composed of subunits with the identical primary structure. it has been believed that the protein structure of these subunits is the same. ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) comprises eight large subunits with the identical amino acid sequence and eight small subunits. rotation of the side chains of the lysine residues, lys-21 and lys-305, in each of the eight large subunits in spinach rubisco in two ways produces microheterogeneity among the subunits. thes ... | 2000 | 11011141 |
| nuclear apoptosis induced by isolated mitochondria. | we isolated and purified mitochondria from mouse livers and spinach leaves. when added into egg extracts of xenopus laevis, they caused nuclei of mouse liver to undergo apoptotic changes. chromatin condensation, margination and dna ladder were observed. after incubating isolated mitochondria in some hypotonic solutions, and centrifuging these mixtures at high speed, we got mitochondrial supernatants. it was found that in the absence of cytosolic factor, the supernatant alone was able to induce a ... | 2000 | 11032174 |
| protein translocation within chloroplast is similar in euglena and higher plants. | it is currently thought that chloroplasts of higher plants were derived from endosymbiont oxygenic photosynthetic bacteria (primary endosymbiosis), while euglena, a photosynthetic protista, gained chloroplasts by secondary endosymbiosis (i.e., incorporation of a photosynthetic eukaryote into heterotrophic eukaryotic host). to examine if the protein transport inside chloroplasts is similar between these organisms, we carried out heterologous protein import experiments with euglena precursor prote ... | 2000 | 11032741 |
| the structure of the chloroplast f1-atpase at 3.2 a resolution. | the structure of the f(1)-atpase from spinach chloroplasts was determined to 3.2 a resolution by molecular replacement based on the homologous structure of the bovine mitochondrial enzyme. the crystallized complex contains four different subunits in a stoichiometry of alpha(3)beta(3)gammaepsilon. subunit delta was removed before crystallization to improve the diffraction of the crystals. the overall structure of the noncatalytic alpha-subunits and the catalytic beta-subunits is highly similar to ... | 2001 | 11032839 |
| binding to 14-3-3 proteins is not sufficient to inhibit nitrate reductase in spinach leaves. | to assess the role of 14-3-3 proteins in the magnesium-dependent inhibition of nitrate reductase (nr) we tested the effect of magnesium on nr binding to 14-3-3s by coimmunoprecipitation and gel filtration. the stability of the 14-3-3 complex of nr was, unlike its activity, unaffected by magnesium. we therefore conclude that binding to 14-3-3s per se does not inhibit nr. magnesium inhibited 14-3-3-bound nr much more strongly than 14-3-3-free nr. 14-3-3s possibly reinforce nr inhibition by magnesi ... | 2000 | 11034332 |
| revalidation and long-term stability of national institute of standards and technology standard reference materials 1566, 1567, 1568, and 1570. | multiple units of standard reference materials (srms) 1566 oyster tissue, 1567 wheat flour, 1568 rice flour, and 1570 trace elements in spinach, produced by the national institute of standards and technology (nist, then the national bureau of standards), were analyzed 17-20 years after the original certification dates and 12-15 years after the certificates became invalid. instrumental neutron activation analysis and thermal neutron prompt gamma-ray activation analysis were used to measure mass f ... | 2000 | 11048853 |
| determination of thirteen common elements in food samples by inductively coupled plasma atomic emission spectrometry: comparison of five digestion methods. | five sample digestion procedures were evaluated for the determination of al, b, ca, cu, fe, k, mg, mn, na, p, s, sr, and zn in food samples by inductively coupled plasma atomic emission spectrometry. the 5 procedures include dry ashing at 500 degrees c, wet digestion with hno3-hclo4, microwave digestion with hno3, microwave digestion with hno3-h2o2, and microwave digestion with hno3-h2o2-hf. for microwave digestion with hno3-h2o2-hf, silicon (iv) oxide was used to eliminate the excess hf, making ... | 2000 | 11048863 |
| crystal structure of paprika ferredoxin-nadp+ reductase. implications for the electron transfer pathway. | cdna of capsicum annuum yolo wonder (paprika) has been prepared from total cellular rna, and the complete gene encoding paprika ferredoxin-nadp(+) reductase (pfnr) precursor was sequenced and cloned from this cdna. fusion to a t7 promoter allowed expression in escherichia coli. both native and recombinant pfnr were purified to homogeneity and crystallized. the crystal structure of pfnr has been solved by patterson search techniques using the structure of spinach ferredoxin-nadp(+) reductase as s ... | 2001 | 11053431 |
| structural and kinetic characterization of an archaeal beta-class carbonic anhydrase. | the beta-class carbonic anhydrase from the archaeon methanobacterium thermoautotrophicum (cab) was structurally and kinetically characterized. analytical ultracentrifugation experiments show that cab is a tetramer. circular dichroism studies of cab and the spinacia oleracea (spinach) beta-class carbonic anhydrase indicate that the secondary structure of the beta-class enzymes is predominantly alpha-helical, unlike that of the alpha- or gamma-class enzymes. extended x-ray absorption fine structur ... | 2000 | 11073902 |
| overexpression and characterization of carboxyl-terminal processing protease for precursor d1 protein: regulation of enzyme-substrate interaction by molecular environments. | ctpa, which is classified as a novel type of serine protease with a ser/lys catalytic dyad, is responsible for the c-terminal processing of precursor d1 protein (pd1) of the photosystem ii reaction center, a process that is indispensable for the integration of water-splitting machinery in photosynthesis. in this study, overexpression in escherichia coli and one-step purification of spinach ctpa were carried out to analyze the characteristics of this new type of protease and to elucidate the mole ... | 2001 | 11099501 |
| overproduction of spinach betaine aldehyde dehydrogenase in escherichia coli. structural and functional properties of wild-type, mutants and e. coli enzymes. | betaine aldehyde dehydrogenase (badh) catalyzes the last step in the synthesis of the osmoprotectant glycine betaine from choline. although betaine aldehyde has been thought to be a specific substrate for badh, recent studies have shown that human and sugar beet badhs also catalyze the oxidation of omega-aminoaldehydes. to characterize the kinetic and stability properties of spinach badh, five kinds of expression vectors encoding full length, mature, e103q, e103k, and chimera badhs were construc ... | 2000 | 11106411 |
| purification of ferredoxins and their reaction with purified reaction center complex from the green sulfur bacterium chlorobium tepidum. | four ferredoxin (fd) fractions, namely, fda-d were purified from the green sulfur bacterium chlorobium tepidum. their absorption spectra are typical of 2[4fe-4s] cluster type fds with peaks at about 385 and 280 nm and a shoulder at about 305 nm. the a(385)/a(280) ratios of the purified fds were 0.76-0.80. analysis of the n-terminal amino acid sequences of these fds (15-25 residues) revealed that those of fda and fdb completely agree with those deduced from the genes, fdx3 and fdx2, respectively, ... | 2001 | 11115649 |
| choline import into chloroplasts limits glycine betaine synthesis in tobacco: analysis of plants engineered with a chloroplastic or a cytosolic pathway. | the biosynthesis of the osmoprotectant glycine betaine (glybet) is a target for metabolic engineering to enhance stress resistance in crops. certain plants synthesize glybet in chloroplasts via a two-step oxidation of choline (cho). in previous work, a chloroplastic glybet synthesis pathway was inserted into tobacco (which lacks glybet) by expressing spinach choline monooxygenase (cmo). the transformants had low cmo enzyme activity, and produced little glybet (less than or = 70 nmol g(-1) fresh ... | 2000 | 11120642 |
| studies on the topology of the protein import channel in relation to the plant mitochondrial processing peptidase integrated into the cytochrome bc1 complex. | the mitochondrial processing peptidase (mpp) specifically cleaves n-terminal targeting signals from hundreds of nuclear-encoded, matrix-targeted precursor proteins. in contrast to yeast and mammals, the plant mpp is an integral component of the respiratory cytochrome bc1 complex. the topology of the protein import channel in relation to mpp/bc1 in plants was studied using chimeric precursors containing truncated cytochrome b2 (cyt b2) proteins of 55-167 residues in length, fused to dihydrofolate ... | 2000 | 11123802 |
| cross-reconstitution of various extrinsic proteins and photosystem ii complexes from cyanobacteria, red algae and higher plants. | photosystem ii (psii) contains different extrinsic proteins required for oxygen evolution among different organisms. cyanobacterial psii contains the 33 kda, 12 kda proteins and cytochrome (cyt) c-550; red algal psii contains a 20 kda protein in addition to the three homologous cyanobacterial proteins; whereas higher plant psii contains the 33 kda, 23 kda and 17 kda proteins. in order to understand the binding and functional properties of these proteins, we performed cross-reconstitution experim ... | 2000 | 11134421 |
| estimation of carotenoid bioavailability from fresh stir-fried vegetables using an in vitro digestion/caco-2 cell culture model. | we previously developed an in vitro model to estimate the relative bioavailability of carotenoids from a meal prepared using commercial baby foods. the general applicability of this model was tested using a stir-fried meal consisting of fresh spinach, fresh carrots, tomato paste, and vegetable oil. after in vitro digestion of the cooked meal, the aqueous fraction was separated from residual oil droplet and solids by centrifugation to quantify micellarized carotenoids. the percentages of lutein, ... | 2000 | 11137895 |
| characterization of carotenoid and chlorophyll photooxidation in photosystem ii. | photosystem ii (psii) contains two accessory chlorophylls (chl(z), ligated to d1-his118, and chl(d), ligated to d2-his117), carotenoid (car), and heme (cytochrome b(559)) cofactors that function as alternate electron donors under conditions in which the primary electron-donation pathway from the o(2)-evolving complex to p680(+) is inhibited. the photooxidation of the redox-active accessory chlorophylls and car has been characterized by near-infrared (near-ir) absorbance, shifted-excitation raman ... | 2001 | 11141071 |
| inhibition of escherichia coli acetyl coenzyme a carboxylase by acyl-acyl carrier protein. | escherichia coli acetyl coenzyme a carboxylase (acc), the first enzyme of the fatty acid biosynthetic pathway, is inhibited by acylated derivatives of acyl carrier protein (acp). acp lacking an acyl moiety does not inhibit acc. acylated derivatives of acp having chain lengths of 6 to 20 carbon atoms were similarly inhibitory at physiologically relevant concentrations. the observed feedback inhibition was specific to the protein moiety, as shown by the inability of the palmitoyl thioester of spin ... | 2001 | 11157970 |
| maintaining methylation activities during salt stress. the involvement of adenosine kinase. | synthesis of the compatible osmolyte gly betaine is increased in salt-stressed spinach (spinacia oleracea). gly betaine arises by oxidation of choline from phosphocholine. phosphocholine is synthesized in the cytosol by three successive s-adenosyl-met-dependent n-methylations of phosphoethanolamine. with each transmethylation, a molecule of s-adenosylhomo-cys (sah) is produced, a potent inhibitor of s-adenosyl-met-dependent methyltransferases. we examined two enzymes involved in sah metabolism: ... | 2001 | 11161043 |
| overexpression of 3-ketoacyl-acyl-carrier protein synthase iiis in plants reduces the rate of lipid synthesis. | a cdna coding for 3-ketoacyl-acyl-carrier protein (acp) synthase iii (kas iii) from spinach (spinacia oleracea; so kas iii) was used to isolate two closely related kas iii clones (ch kas iii-1 and ch kas iii-2) from cuphea hookeriana. both ch kas iiis are expressed constitutively in all tissues examined. an increase in the levels of 16:0 was observed in tobacco (nicotiana tabacum, wt-sr) leaves overexpressing so kas iii when under the control of the cauliflower mosaic virus-35s promoter and in a ... | 2001 | 11161065 |
| the sequence and secondary structure of the 3'-utr affect 3'-end maturation, rna accumulation, and translation in tobacco chloroplasts. | rna maturation and modulation of rna stability play important roles in chloroplast gene expression. in vitro and in vivo studies have shown that both the 5'- and 3'-untranslated regions (utrs) contain sequence and structural elements that guide these processes, and interact with specific proteins. we have previously characterized the spinach chloroplast petd 3'-utr in detail by in vitro approaches. this stem-loop forming sequence is a weak terminator but is required for rna maturation and also e ... | 2000 | 11197327 |
| effect of natural antioxidants and apocynin on lps-induced endotoxemia in rabbit. | the objective of this study was to compare the prophylactic effects of the natural antioxidant from spinach (nao) and apocynin, on the hepatic oxidative stress and liver damage induced by lipopolysaccharide (lps). male new zealand rabbits were challenged with lps with or without 8 days of antioxidant pretreatment. pretreatment with nao, but not apocynin, significantly (p < 0.05) decreased the levels of hydroperoxides and malondialdehyde (mda) in the liver cytosolic fraction and the activity of n ... | 2000 | 11211238 |
| contents of minerals in green leafy vegetables cultivated in soil fortified with different chemical fertilizers. | content of selected minerals in spinach (spinacea oleracea) and ambat chuka (rumex vesicarius) cultivated in soil fortified with different chemical fertilizers was determined in a pot experiment. addition of npk (nitrogen, phosphorus and potassium) fertilizer along with micronutrients, iron and zinc, enhanced the concentration of zinc, iron and magnesium in selected green leafy vegetables markedly (p < 0.05), while the concentration of copper was not altered significantly (p > 0.05). potassium c ... | 2001 | 11213164 |
| cytosolic glutamine synthetase and not nitrate reductase from the green alga chlamydomonas reinhardtii is phosphorylated and binds 14-3-3 proteins. | the nitrate reductase activity from chlamydomonas reinhardtii was not altered when extracts were incubated with yeast 14-3-3 proteins in the presence of mg-atp. however, the c. reinhardtii extracts contained 14-3-3 proteins capable of inhibiting the spinach nitrate reductase, raising the question of their physiological substrates. two c. reinhardtii proteins of about 48 and 35 kda were eluted from 14-3-3 affinity chromatography columns and bound to 14-3-3s in overlay assays. the 48-kda protein c ... | 2001 | 11216847 |
| combined hplc-ms and hplc-nmr on-line coupling for the separation and determination of lutein and zeaxanthin stereoisomers in spinach and in retina. | the determination and unambiguous identification of carotenoid stereoisomers from biological tissues, avoiding isomerization and oxidation due to the extraction process, is still a major challenge. particularly, the analysis of lutein and zeaxanthin stereoisomers is of great importance, as these are the main constituents of the macula lutea, the central part of the human retina, and act as possible agents in the prevention and treatment of age-related macular degeneration (amd). by combining a m ... | 2001 | 11217779 |
| cloning and expression of a nuclear encoded plastid specific 33 kda ribonucleoprotein gene (33rnp) from pea that is light stimulated. | we report the cloning and sequencing of both cdna and genomic dna of a 33 kda chloroplast ribonucleoprotein (33rnp) from pea. the analysis of the predicted amino acid sequence of the cdna clone revealed that the encoded protein contains two rna binding domains, including the conserved consensus ribonucleoprotein sequences cs-rnp1 and cs-rnp2, on the c-terminus half and the presence of a putative transit peptide sequence in the n-terminus region. the phylogenetic and multiple sequence alignment a ... | 2001 | 11223256 |
| microbiological quality of fresh leafy vegetables, salad components and ready-to-eat salads: an evidence of inhibition of listeria monocytogenes in tomatoes. | a total of 116 samples of 11 different fresh vegetables from a local market generally consumed in raw form as well as 12 samples of ready-to-eat green salads procured from three grade 1 and 2 restaurants in mumbai, india were examined for overall microbial quality in terms of bacterial, mold and coliform levels and incidence of pathogens such as listeria and yersinia. standard procedures and media were used for isolation and identification studies. thoroughly washed samples of 26 leafy vegetable ... | 2001 | 11225173 |
| the evolution of glutamate synthase. | dna coding for the ferredoxin-dependent glutamate synthase (ec 1.4.7.1) of spinach chloroplasts has been cloned and sequenced. it consists of 5015 bp and starts with the codon for the n-terminal cysteine of the mature protein. ferredoxin-dependent glutamate synthase is one of the key enzymes in the early stages of ammonia assimilation in plants, algae and cyanobacteria. in addition to the ferredoxin-dependent enzyme, there are two other forms of glutamate synthase, one of which uses nadh as the ... | 2000 | 11254103 |
| importance of the n-terminal sequence of the extrinsic 23 kda polypeptide in photosystem ii in ion retention in oxygen evolution. | the function of the extrinsic 23 kda polypeptide (oec23) in photosystem ii (ps ii) is to retain ca(2+) and cl(-) during the s-state turnover of the mn cluster in photosynthetic oxygen evolution. recombinant oec23s from several plant species were produced in escherichia coli to characterize the molecular mechanism of the oec23 function then used in reconstitution experiments. one tobacco isoform, oec23 (2af), had much less oxygen-evolving activity than the spinach and cucumber oec23s when ps ii a ... | 2001 | 11257522 |
| genotoxic effects after in vivo exposure of vegetable extracts containing heavy metals from the dhapa area of calcutta, india. i. effects of cauliflower, spinach and radish. | several reports have indicated that the sewage-fed vegetables of the dhapa area, near the city of calcutta, contain a very high amount of heavy metals. currently 800 ha of land is being utilised throughout the year to cultivate more than eight types of vegetables, with a production of about 147 tonnes per day. a major population of calcutta consumes these vegetables grown in the dhapa area. recently there has been huge pressure on the state government to ban vegetables grown in the dhapa area fo ... | 2001 | 11259852 |
| dual targeting of spinach protoporphyrinogen oxidase ii to mitochondria and chloroplasts by alternative use of two in-frame initiation codons. | protoporphyrinogen oxidase (protox) is the final enzyme in the common pathway of chlorophyll and heme biosynthesis. two protox isoenzymes have been described in tobacco, a plastidic and a mitochondrial form. we isolated and sequenced spinach protox cdna, which encodes a homolog of tobacco mitochondrial protox (protox ii). alignment of the deduced amino acid sequence between protox ii and other tobacco mitochondrial protox homologs revealed a 26-amino acid n-terminal extension unique to the spina ... | 2001 | 11274159 |
| temperature response of leaf photosynthetic capacity in seedlings from seven temperate tree species. | seedlings of seven temperate tree species (acer pseudoplatanus l., betula pendula roth, fagus sylvatica l., fraxinus excelsior l., juglans regia l., quercus petraea matt. liebl. and quercus robur l.) were grown in a nursery under neutral filters transmitting 45% of incident global irradiance. during the second or third year of growth, leaf photosynthetic capacity (i.e., maximal carboxylation rate, vcmax, maximal photosynthetic electron transport rate, jmax, and dark respiration, rd) was estimate ... | 2001 | 11276416 |
| assembled f1-(alpha beta ) and hybrid f1-alpha 3beta 3gamma -atpases from rhodospirillum rubrum alpha, wild type or mutant beta, and chloroplast gamma subunits. demonstration of mg2+versus ca2+-induced differences in catalytic site structure and function. | refolding together the expressed alpha and beta subunits of the rhodospirillum rubrum f(1)(rf(1))-atpase led to assembly of only alpha(1)beta(1) dimers, showing a stable low mgatpase activity. when incubated in the presence of alcl(3), naf and either mgad(t)p or caad(t)p, all dimers associated into closed alpha(3)beta(3) hexamers, which also gained a low caatpase activity. both hexamer atpase activities exhibited identical rates and properties to the open dimer mgatpase. these results indicate t ... | 2001 | 11278351 |
| determination of photosystem ii subunits by matrix-assisted laser desorption/ionization mass spectrometry. | photosystem ii of higher plants and cyanobacteria is composed of more than 20 polypeptide subunits. the pronounced hydrophobicity of these proteins hinders their purification and subsequent analysis by mass spectrometry. this paper reports the results obtained by application of matrix-assisted laser desorption/ionization mass spectrometry directly to isolated complexes and thylakoid membranes prepared from cyanobacteria and spinach. changes in protein contents following physiopathological stimul ... | 2001 | 11278383 |
| class ii recombinant phosphoribosyl diphosphate synthase from spinach. phosphate independence and diphosphoryl donor specificity. | a recombinant form of spinach (spinacia oleracea) phosphoribosyl diphosphate (prpp) synthase isozyme 3 resembling the presumed mature enzyme has been synthesized in an escherichia coli strain in which the endogenous prpp synthase gene was deleted, and has been purified to near homogeneity. contrary to other prpp synthases the activity of spinach prpp synthase isozyme 3 is independent of p(i), and the enzyme is inhibited by ribonucleoside diphosphates in a purely competitive manner, which indicat ... | 2001 | 11278632 |
| growth interactions during bacterial colonization of seedling rootlets. | rootlet elongation and bacterial growth on rootlets were determined after inoculation of cucumber and spinach seedlings with pseudomonas strains differing in production of siderophores and hcn. siderophore producers grew more profusely than nonproducers on both species and promoted rootlet elongation on cucumber. coinoculation of siderophore producers and nonproducers resulted in restricted growth of the latter. the total populations of nonproducers of hcn in the presence of hcn producers were n ... | 2001 | 11282653 |
| molecular cloning and functional characterization of two kinds of betaine-aldehyde dehydrogenase in betaine-accumulating mangrove avicennia marina (forsk.) vierh. | glycinebetaine is an important osmoprotectant in bacteria, plants, and animals, but only little information is available on the synthesis of glycinebetaine in tree plants. among four mangrove species, glycinebetaine could be detected only in avicennia marina. pinitol was the main osmoprotectant in the other three species. the level of glycinebetaine in a. marina increased under high salinity. betaine-aldehyde dehydrogenase (badh) was detected in all four species, but choline monooxygenase could ... | 2001 | 11292080 |
| listeria species in raw and ready-to-eat foods from restaurants. | from september 1999 to march 2000, meat (pork, beef, and chicken), fish (salmon, hake, and sole), vegetable (lettuce and spinach), and spanish potato omelette samples obtained at restaurants were collected and tested for the occurrence of listeria spp. listeria monocytogenes was isolated from 3 (2.9%) out of 103 studied samples. other species isolated were listeria grayi (13.6%), listeria innocua (1.9%), listeria ivanovii (5.8%), listeria seeligeri (3.9%), and listeria welshimeri (1.9%). listeri ... | 2001 | 11307896 |
| assessment of degradation and intestinal cell uptake of carotenoids and chlorophyll derivatives from spinach puree using an in vitro digestion and caco-2 human cell model. | although numerous studies have demonstrated the health benefits of chlorophyll derivatives, information regarding the digestion, absorption, and metabolism of these phytochemicals is quite limited. to better understand the digestion of these pigments, green vegetables including fresh spinach puree (fsp), heat- and acid-treated spinach puree (hasp), and zncl(2)-treated spinach puree (znsp) were subjected to an in vitro digestion method which simulates both the gastric and small intestinal phases ... | 2001 | 11308371 |
| purification and cloning of chloroplast 6-phosphogluconate dehydrogenase from spinach. cyanobacterial genes for chloroplast and cytosolic isoenzymes encoded in eukaryotic chromosomes. | previous attempts to purify chloroplast 6-phosphogluconate dehydrogenase (cp6pgdh), a key enzyme of the oxidative pentose phosphate pathway, have been unsuccessful due to rapid activity loss. an efficient purification protocol was developed and the enzyme from spinach leaves was purified 1000-fold to apparent homogeneity with a specific activity of 60 u.mg-1. the enzyme is a homodimer with subunits of 50 kda. antibodies raised against the purified cp6pgdh detected a 53-kda protein from a crude e ... | 2001 | 11322889 |
| characterization of monoclonal antibodies against ascorbate peroxidase isoenzymes: purification and epitope-mapping using immunoaffinity column chromatography. | we have developed three monoclonal antibodies against spinach chloroplastic (chl-mab3 and chl-mab6) and cytosolic (cyt-mab1) ascorbate peroxidase (apx) isoenzymes to analyze the cross-reactivity and the structure of the epitopes for each monoclonal antibody. all three antibodies reacted specifically with their respective isoenzymes, but none cross-reacted with the others. immunoreactive fragments in proteolytic recombinant apx isoenzymes were detected by means of the absorption on the correspond ... | 2001 | 11325538 |
| d1-asp170 is structurally coupled to the oxygen evolving complex in photosystem ii as revealed by light-induced fourier transform infrared difference spectroscopy. | we report both mid-frequency (1800-1200 cm(-)(1)) and low-frequency (670-350 cm(-)(1)) s(2)/s(1) ftir difference spectra of photosystem ii (psii) particles isolated from wild-type and d1-d170h mutant cells of the cyanobacterium synechocystis sp. pcc 6803. both mid- and low-frequency s(2)/s(1) spectra of the synechocystis wild-type psii particles closely resemble those from spinach psii samples, which confirms an earlier result by noguchi and co-workers [noguchi, t., inoue, y., and tang, x.-s. (1 ... | 2001 | 11329301 |
| [cloning and characterization of cmo gene from atriplex hortensis]. | glycine betaine is a widespread osmopretectant existed in many organisms. in higher plant, glycine betaine is synthesized via a two-sep oxidation reaction: choline-->betaine aldehyde-->glycine betaine. the first step, also the speed-limiting step, is catalyzed by choline monooxygenase(cmo). choosing halophyte atriplex hortensis as material, we constructed a salt stress-induced cdna library, and isolated a 1.77 kb length cdna clone with spinach cmo cdna as probe. the sequencing result showed a co ... | 2001 | 11330176 |
| a study on transfer factors of 60co and 65zn from soil to plants in the tropical environment of bangladesh. | soil to plant transfer factor (tf) of 60co and 65zn was determined from radioisotope experiments on plants grown in pots under outdoor ambient tropical conditions for three growing seasons (1995-1998). the tfs were obtained for different plants/crops such as, rice, bean, peanuts pineapple, cabbage, tomato, spinach and grass. the average tf values of 60co are found to be 0.087. 0.15, 0.12, 0.67, 0.28, 0.79, 1.03 and 0.34 respectively for the above mentioned plants/crops. in case of 65zn, the aver ... | 2001 | 11336414 |
| molecular biology of the plastidic phosphorylated serine biosynthetic pathway in arabidopsis thaliana. | serine biosynthesis in plants proceeds by two pathways; the glycolate pathway which is associated with photorespiration and the pathway from 3-phosphoglycerate which is presumed to take place in the plastids. the 3-phosphoglycerate pathway (phosphorylated pathway) involves three enzymes catalyzing three sequential reactions: 3-phosphoglycerate dehydrogenase (pgdh), 3-phosphoserine aminotransferase (psat) and 3-phosphoserine phosphatase (psp). cdna and genomic clones encoding these three enzymes ... | 2001 | 11354602 |
| analysis of the activity of promoters from two photosynthesis-related genes psaf and peth of spinach in a monocot plant, rice. | the subunit iii of photosystem i and ferredoxin-nadp(+)-oxidoreductase are encoded by nuclear genes, namely psaf and peth. the activity of their promoters from spinach has been evaluated in transgenic tobacco earlier. evaluation of the activity of these dicotyledoneae-specific promoters has been carried out in a monocot system (i.e. rice) by transient gene expression system, based on electroporation-mediated gene delivery into protoplasts from leaves and roots. it has been found that various pro ... | 2000 | 11355632 |
| determination of phylloquinone and menaquinones in food. effect of food matrix on circulating vitamin k concentrations. | fluctuations in international normalized ratio values are often ascribed to dietary changes in vitamin k intake. here we present a database with vitamin k(1) and k(2) contents of a wide variety of food items. k(1) was mainly present in green vegetables and plant margarins, k(2) in meat, liver, butter, egg yolk, natto, cheese and curd cheese. to investigate the effect of the food matrix on vitamin k bioavailability, 6 healthy male volunteers consumed either a detergent-solubilized k(1) (3.5 micro ... | 2000 | 11356998 |
| two-cistron system overexpression of chloroplast glyceraldehyde-3-phosphate dehydrogenase subunit b and b-derivatives from spinach in escherichia coli. | a gene coding for the subunit b (gapb) of chloroplast glyceraldehyde-3-phosphate dehydrogenase from spinach and its two derivatives (gapbc) lacking the gapb-specific c-terminal extension have been cloned by rt-pcr. these three genes have been overexpressed with full activity in escherichia coli when a two-cistron expression system controlled by an inducible promoter p(trc) is used. with a suitable base composition of the first cistron, the expression level of gapb and the derivatives gapbc are e ... | 2001 | 11388796 |
| topical and oral administration of the natural water-soluble antioxidant from spinach reduces the multiplicity of papillomas in the tg.ac mouse model. | the tg.ac mouse carrying the v-ha-ras structural gene is a useful model for the study of chemical carcinogens, especially those acting via non-genotoxic mechanisms. this study evaluated the efficacy of the non-toxic, water-soluble antioxidant from spinach, natural antioxidant (nao), in reducing skin papilloma induction in female hemizygous tg.ac mice treated dermally five times over 2.5 weeks with 2.5 microg 12-o-tetradecanoylphorbol-13-acetate (tpa). the tpa-only group was considered as a contr ... | 2001 | 11397555 |