| stability of food allergens to digestion in vitro. | an integral part of the safety assessment of genetically modified plants is consideration of possible human health effects, especially food allergy. prospective testing for allergenicity of proteins obtained from sources with no prior history of causing allergy has been difficult because of the absence of valid methods and models. food allergens may share physicochemical properties that distinguish them from nonallergens, properties that may be used as a tool to predict the inherent allergenicit ... | 1996 | 9631091 |
| the role of acyl carrier protein isoforms from cuphea lanceolata seeds in the de-novo biosynthesis of medium-chain fatty acids. | to investigate the role of acyl carrier protein (acp) in determining the fate of the acyl moieties linked to it in the course of de-novo fatty acid biosynthesis in higher plants, we carried out in vitro experiments to reconstitute the fatty acid synthase (fas) reaction in extracts of spinach (spinacia oleracea l.) leaves, rape (brassica napus l.) seeds and cuphea lanceolata ait. seeds. the action of two major c. lanceolata acp isoforms (acp 1 and acp 2) compared to acp from escherichia coli was ... | 1998 | 9637071 |
| ilarviruses encode a cucumovirus-like 2b gene that is absent in other genera within the bromoviridae. | we found that rna 2 of the four ilarviruses sequenced to date encodes an additional conserved open reading frame (orf), 2b, that overlaps the 3' end of the previously known orf, 2a. a novel rna species of 851 nucleotides was found to accumulate to high levels in plants infected with spinach latent virus (splv). further analysis showed that rna 4a is a subgenomic rna of rna 2 and encodes all of orf 2b. moreover, a protein species of the size expected for splv orf 2b was translated in vitro from t ... | 1998 | 9658153 |
| the complete nucleotide sequence of prune dwarf ilarvirus rna-1. | the sequence of prune dwarf ilarvirus (pdv) rna-1 has been determined; it consists of 3,374 nucleotides and contains a single open reading frame of 3,168 nucleotides. the putative translation product is 1,055 amino acids in length with a calculated molecular mass of 118.9 kda. both the nucleic acid and the translated amino acid sequences show stronger homology to the corresponding rna-1 and orf-1 of apple mosaic ilarvirus and alfalfa mosaic alfamovirus than to spinach latent mosaic ilarvirus or ... | 1997 | 9672650 |
| electrophysiological evidence for the typicality effect of human cognitive categorization. | event-related brain potentials (erps) were recorded from 14 normal subjects during a category verification task. stimulus words were selected from 17 semantic categories (e.g. 'vegetables'). half of the words were typical category members (e.g. 'carrot', 'spinach') and the other half were atypical (e.g. 'parsley', 'asparagus'). subjects were required to judge whether each stimulus belonged to a target category ('vegetables' or 'sports') or a non-target category. for the non-target category, the ... | 1998 | 9641249 |
| characterisation of an arabidopsis cdna encoding a thylakoid lumen protein related to a novel 'pentapeptide repeat' family of proteins. | we have cloned an arabidopsis cdna encoding a novel thylakoid lumen protein, p17.4, that has been previously isolated from lumen extracts of spinach chloroplasts. the protein is synthesised with a bipartite presequence containing a sec-type lumen-targeting signal peptide and the precursor protein is imported into the lumen of pea chloroplasts. the encoded protein is homologous to an anabaena protein that is essential for correct glycolipid localisation, and is also related to at least 16 unassig ... | 1998 | 9654141 |
| electrospray-ionization mass spectrometry of intact intrinsic membrane proteins. | membrane proteins drive and mediate many essential cellular processes making them a vital section of the proteome. however, the amphipathic nature of these molecules ensures their detailed structural analysis remains challenging. a versatile procedure for effective electrospray-ionization mass spectrometry (esi-ms) of intact intrinsic membrane proteins purified using reverse-phase chromatography in aqueous formic acid/isopropanol is presented. the spectra of four examples, bacteriorhodopsin and ... | 1998 | 9655347 |
| the escherichia coli citrate carrier citt: a member of a novel eubacterial transporter family related to the 2-oxoglutarate/malate translocator from spinach chloroplasts. | under anoxic conditions in the presence of an oxidizable cosubstrate such as glucose or glycerol, escherichia coli converts citrate to acetate and succinate. two enzymes are specifically required for the fermentation of the tricarboxylic acid, i.e., a citrate uptake system and citrate lyase. here we report that the open reading frame (designated citt) located at 13.90 min on the e. coli chromosome between rna and the citrate lyase genes encodes a citrate carrier. e. coli transformed with a plasm ... | 1998 | 9696764 |
| spinach csp41, an mrna-binding protein and ribonuclease, is homologous to nucleotide-sugar epimerases and hydroxysteroid dehydrogenases. | spinach csp41 is part of a protein complex that binds to the 3' untranslated region (utr) of petd precursor-mrna, a chloroplast gene encoding subunit iv of the cytochrome b6/f complex. csp41 cleaves the 3'-utr of petd mrna within the stem-loop structure, suggesting a key role in the control of chloroplast mrna stability. we discovered that csp41 is homologous to nucleotide-sugar epimerases and hydroxysteroid dehydrogenases while seeking distant homologs of these enzymes with a hidden markov mode ... | 1998 | 9675122 |
| 3-hydroxy-3-methylglutaryl-coenzyme a reductase kinase and sucrose-phosphate synthase kinase activities in cauliflower florets: ca2+ dependence and substrate specificities. | plant 3-hydroxy-3-methylglutaryl-coa reductase(hmgr; ec 1.1.1.34) and sucrose-phosphate synthase (sps; ec 2.4.1.14) and synthetic peptides designed from the known phosphorylation sites of plant hmgr (sams*: kshmkynrstkdvk), rat acetyl-coa carboxylase (sams: hmrsamsglhlvkrr), spinach sps (sp2: grrjrrissvejjdkk), and spinach nadh:nitrate reductase (nr6: gptlkrtastpfjnttsk) were used to characterize kinase activities from cauliflower (brassica oleracea l. ) inflorescences. the three major peaks of ... | 1998 | 9675040 |
| investigation of the ability of proteolytic clostridium botulinum to multiply and produce toxin in fresh italian pasta. | the ability of proteolytic clostridium botulinum (types a, b, and f) to produce toxin in filled fresh italian pasta (tortelli) packed under a modified atmosphere was investigated. four types of tortelli (filled with artichoke, meat, ricotta-spinach, or salmon) were inoculated with a suspension of heat-shocked spores to give an initial concentration of approximately 10(3) spores per piece. samples were incubated at both 12 and 20 degrees c for up to 50 days and examined at selected time intervals ... | 1998 | 9713759 |
| correlation between protein flexibility and electron transfer from qa-* to qb in psii membrane fragments from spinach. | to analyze a possible correlation between the extent of qa-* reoxidation and protein dynamics, fluorometric and mössbauer spectroscopic measurements were performed in photosystem ii membrane fragments from spinach. numerical evaluation of the flash-induced change of the normalized fluorescence quantum yield revealed that the extent of reoxidation starts to decrease below 275 k and is almost completely suppressed at 230 k. detailed analyses of mössbauer spectra measured at different temperatures ... | 1998 | 9708974 |
| hydrogen bonding of redox-active tyrosine z of photosystem ii probed by ftir difference spectroscopy. | the tyrz./tyrz ftir difference spectrum is reported for the first time in mn-depleted photosystem ii (ps ii)-enriched membranes of spinach, in ps ii core complexes of synechocystis sp. pcc 6803 wt, and in the mutant lacking tyrd (d2-tyr160phe). in synechocystis, the v7'a(co) and delta(coh) infrared modes of tyrz are proposed to account at 1279 and 1255 cm-1. the frequency of these modes indicate that tyrz is protonated at ph 6 and involved in a strong hydrogen bond to the side chain of a histidi ... | 1998 | 9692943 |
| transcription from heterologous rrna operon promoters in chloroplasts reveals requirement for specific activating factors. | the plastid rrna (rrn) operon in chloroplasts of tobacco (nicotiana tabacum), maize, and pea is transcribed by the plastid-encoded plastid rna polymerase from a sigma70-type promoter (p1). in contrast, the rrn operon in spinach (spinacia oleracea) and mustard chloroplasts is transcribed from the distinct pc promoter, probably also by the plastid-encoded plastid rna polymerase. primer-extension analysis reported here indicates that in arabidopsis both promoters may be active. to understand promot ... | 1998 | 9701604 |
| d-ribulose-5-phosphate 3-epimerase: cloning and heterologous expression of the spinach gene, and purification and characterization of the recombinant enzyme. | we have achieved, to our knowledge, the first high-level heterologous expression of the gene encoding d-ribulose-5-phosphate 3-epimerase from any source, thereby permitting isolation and characterization of the epimerase as found in photosynthetic organisms. the extremely labile recombinant spinach (spinacia oleracea l.) enzyme was stabilized by dl-alpha-glycerophosphate or ethanol and destabilized by d-ribulose-5-phosphate or 2-mercaptoethanol. despite this lability, the unprecedentedly high sp ... | 1998 | 9733539 |
| adp-glucose pyrophosphorylase from potato tubers. site-directed mutagenesis studies of the regulatory sites. | several lysines (lys) were determined to be involved in the regulation of the adp-glucose (glc) pyrophosphorylase from spinach leaf and the cyanobacterium anabaena sp. pcc 7120 (k. ball, j. preiss [1994] j biol chem 269: 24706-24711; y. charng, a.a. iglesias, j. preiss [1994] j biol chem 269: 24107-24113). site-directed mutagenesis was used to investigate the relative roles of the conserved lys in the heterotetrameric enzyme from potato (solanum tuberosum l.) tubers. mutations to alanine of lys- ... | 1998 | 9733546 |
| long-term dietary strawberry, spinach, or vitamin e supplementation retards the onset of age-related neuronal signal-transduction and cognitive behavioral deficits. | recent research has indicated that increased vulnerability to oxidative stress may be the major factor involved in cns functional declines in aging and age-related neurodegenerative diseases, and that antioxidants, e.g., vitamin e, may ameliorate or prevent these declines. present studies examined whether long-term feeding of fischer 344 rats, beginning when the rats were 6 months of age and continuing for 8 months, with diets supplemented with a fruit or vegetable extract identified as being hi ... | 1998 | 9742171 |
| trienzyme treatment for food folate analysis: optimal ph and incubation time for alpha-amylase and protease treatment. | recent reports have indicated that trienzyme treatment before folate determination is essential to obtain the proper folate content in foods. trienzyme treatment is performed by using alpha-amylase and protease for folate extraction from carbohydrate and protein matrices, and folate conjugase for the hydrolysis of polyglutamyl folates. we evaluated the conditions of ph and incubation time for the treatment with alpha-amylase and protease. four food items, including fresh beef, white bread, cow's ... | 1998 | 9742457 |
| expression, purification, and characterization of recombinant ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit nepsilon-methyltransferase. | ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) large subunit (ls) nepsilon-methyltransferase (rubisco lsmt, ec 2.1.1.127) catalyzes methylation of the ls of rubisco. a pea (pisum sativum l. cv laxton's progress no. 9) rubisco lsmt cdna was expressed in escherichia coli, but most of the expressed protein was found in the insoluble fraction as an inclusion body. expression at lower temperatures increased the level of soluble rubisco lsmt and the associated enzymatic activity. however, t ... | 1998 | 9758757 |
| cloning and expression of the glgc gene from agrobacterium tumefaciens: purification and characterization of the adpglucose synthetase. | the gene encoding adpglucose synthetase (ec 2.7.7.27) from agrobacterium tumefaciens was isolated and expressed in escherichia coli. the recombinant protein was purified to electrophoretic homogeneity in steps including ion-exchange and hydrophobic chromatography. the same purification procedure was utilized to purify adpglucose synthetase from a. tumefaciens cells. the enzymes from the two sources were purified and characterized and were found to have identical kinetic, regulatory, and structur ... | 1998 | 9721178 |
| novel defensin subfamily from spinach (spinacia oleracea). | antimicrobial peptides (so-d1-7) were isolated from a crude cell wall preparation from spinach leaves (spinacia oleracea cv. matador) and, judged from their amino acid sequences, six of them (so-d2-7) represented a novel structural subfamily of plant defensins (group iv). group-iv defensins were also functionally distinct from those of groups i-iii. they were active at concentrations < 20 microm against gram-positive (clavibacter michiganensis) and gram-negative (ralstonia solanacearum) bacteria ... | 1998 | 9762899 |
| a simple procedure for purifying the major chloroplast fructose-1,6-bisphosphatase from spinach (spinacia oleracea) and characterization of its stimulation by sub-femtomolar mercuric ions. | a rapid procedure for the purification of the redox-regulated chloroplast fructose-1,6-bisphosphatase [ec 3.1.3.11] from spinach leaf extract to homogeneity is described. no thiol-reducing agents were present during the purification and the enzyme is > 99% in the oxidized form. a rapid procedure to reduce and activate the fru-1,6-p2ase by dithiothreitol in the absence of thioredoxin is described. reduction activates the enzyme up to several hundred-fold when assayed at ph 8.0 with 2 mm mg2+. the ... | 1998 | 9735161 |
| the carboxyl-terminal tripeptide of the manganese-stabilizing protein is required for quantitative assembly into photosystem ii and for high rates of oxygen evolution activity. | the extrinsic manganese stabilizing protein of photosystem ii is required for mn retention by the o2-evolving complex, accelerates the rate of o2 evolution, and protects photosytem ii against photoinhibition. we report results from studies of the in vitro reconstitution of spinach photosytem ii with recombinant manganese stabilizing protein with c-terminal deletions of two, three, and four amino acids. the deletions were the result of amber mutations introduced by site-directed mutagenesis. remo ... | 1998 | 9760261 |
| protective effects of fruits and vegetables against in vivo clastogenicity of cyclosphosphamide or benzo[a]pyrene in mice. | seven fruits and 10 vegetables commonly consumed in germany were investigated for their anticlastogenic potencies against cyclophosphamide (cp) and benzo[a]pyrene (bap) in the in vivo mouse bone marrow micronucleus assay. we detected protective effects in 76.5% and 70.6% of the samples, respectively, and more or less distinct quantitative differences between the various plant materials and the two clastogens investigated. with respect to cp, moderate activities were exerted by sweet cherries, st ... | 1998 | 9734714 |
| a novel, non-redox-regulated nad-dependent malate dehydrogenase from chloroplasts of arabidopsis thaliana l. | we report a novel plastidic nad-dependent malate dehydrogenase (ec 1. 1.1.37), which is not redox-regulated in contrast to its nadp-specific counterpart (ec 1.1.1.82). analysis of isoenzyme patterns revealed a single nad-mdh associated with highly purified chloroplasts isolated from arabidopsis and spinach. a cdna clone encoding the novel enzyme was found in the arabidopsis est data base by sorting all putative clones for nad-dependent malate dehydrogenase. a derived amino acid sequence is very ... | 1998 | 9774405 |
| the crystal structure of nadph:ferredoxin reductase from azotobacter vinelandii. | nadph:ferredoxin reductase (avfpr) is involved in the response to oxidative stress in azotobacter vinelandii. the crystal structure of avfpr has been determined at 2.0 a resolution. the polypeptide fold is homologous with six other oxidoreductases whose structures have been solved including escherichia coli flavodoxin reductase (ecfldr) and spinach, and anabaena ferredoxin:nadp+ reductases (fnr). avfpr is overall most homologous to ecfldr. the structure is comprised of a n-terminal six-stranded ... | 1998 | 9865948 |
| a novel approach for the crystallization of soluble proteins using non-ionic surfactants. | crystallization trials using three polyoxyethylene surfactants as precipitating agents are described. of the eight soluble proteins screened, five were successfully crystallized at the first attempt. these included lysozyme, catalase, ferritin, ribonuclease a and ubiquitin. further work suggested that these surfactants could also be suitable for cryo-crystallographic analysis of crystals. at the concentrations used in the crystallization trials [10-40%(v/v)], they are capable of promoting the fo ... | 1998 | 9867432 |
| serum antioxidant capacity is increased by consumption of strawberries, spinach, red wine or vitamin c in elderly women. | it is often assumed that antioxidant nutrients contribute to the protection afforded by fruits, vegetables, and red wine against diseases of aging. however, the effect of fruit, vegetable and red wine consumption on the overall antioxidant status in human is unclear. in this study we investigated the responses in serum total antioxidant capacity following comsumption of strawberries (240 g), spinach (294 g), red wine (300 ml) or vitamin c (1250 mg) in eight elderly women. total antioxidant capac ... | 1998 | 9868185 |
| signals required for the import and processing of the alternative oxidase into mitochondria. | the critical residues involved in targeting and processing of the soybean alternative oxidase to plant and animal mitochondria was investigated. import of various site-directed mutants into soybean mitochondria indicated that positive residues throughout the length of the presequence were important for import, not just those in the predicted region of amphiphilicity. the position of the positive residues in the c-terminal end of the presequence was also important for import. processing assays of ... | 1999 | 9880497 |
| stoichiometrically bound beta-carotene in the cytochrome b6f complex of oxygenic photosynthesis protects against oxygen damage. | the cytochrome b6f complex of oxygenic photosynthesis carries out "dark reactions" of electron transfer that link the light-driven reactions of the reaction centers, and coupled proton transfer that generates part of the electrochemical potential utilized for atp synthesis. in contrast to the bc1 complex of the respiratory chain, with which there are many structural and functional homologies, the b6f complex contains bound pigment molecules. along with the specifically bound chlorophyll a previo ... | 1999 | 9880536 |
| ribose-5-phosphate isomerase from saccharomyces cerevisiae: purification and molecular analysis of the enzyme. | purification and molecular analysis of ribose-5-phosphate isomerase (ec 5.3.1.6) from saccharomyces cerevisiae is described first time. the enzyme was enriched from a haploid deletion mutant containing the wild-type gene on a multicopy plasmid elaborating the following steps: ammonium sulphate precipitation, interfacial salting out on sepharose 6b, high performance liquid chromatography on fractogel emd deae and on resource phenyl. the enzyme activity was found to be rather unstable possibly cau ... | 1998 | 9763699 |
| [characterization of aldehyde dehydrogenase gene fragment from mung bean vigna radiata using the polymerase chain reaction]. | two degenerate oligonucleotide sequence primers and polymerase chain reactions on total dna have been utilized to clone on 651--bp gene fragment coding the central part of amino acid sequence of an earlier unknown aldehyde dehydrogenase (aldh) from mung bean. the deduced partial amino acid sequence for this aldehyde dehydrogenase shows about 65% sequence identity to aldhs of vibrio cholerae rhodococcus sp., alcaligenes eutrophus and about 45% sequence identity to mammalian aldhs 1 and 2, aldhs o ... | 1998 | 9778740 |
| fruits and vegetables that are sources for lutein and zeaxanthin: the macular pigment in human eyes. | it has been suggested that eating green leafy vegetables, which are rich in lutein and zeaxanthin, may decrease the risk for age related macular degeneration. the goal of this study was to analyse various fruits and vegetables to establish which ones contain lutein and/or zeaxanthin and can serve as possible dietary supplements for these carotenoids. | 1998 | 9828775 |
| the endogenous choline supply limits glycine betaine synthesis in transgenic tobacco expressing choline monooxygenase. | certain plants produce glycine betaine (glybet) in the chloroplast by a two-step oxidation of choline. introducing glybet accumulation into plants that lack it is a well-established target for metabolic engineering because glybet can lessen damage from osmotic stress. the first step in glybet synthesis is catalyzed by choline mono-oxygenase (cmo), a stromal enzyme with a rieske-type [2fe-2s] center. the absence of cmo is the primary constraint on glybet production in glybet-deficient plants such ... | 1998 | 9881168 |
| membrane and receptor modifications of oxidative stress vulnerability in aging. nutritional considerations. | evidence suggests that oxidative stress (os) may contribute to the pathogenesis of age-related decrements in neuronal function and that os vulnerability increases as a function of age. in addition to decreased endogenous protection, increases in os vulnerability may result from changes in membrane lipids and distribution of receptor subtype. using a pc-12 cell model system, we have shown that h2o2 or dopamine (da) exposure induced deficits in the cell's ability to clear (extrude/sequester, e/s) ... | 1998 | 9928436 |
| alternatively spliced mrna variants of chloroplast ascorbate peroxidase isoenzymes in spinach leaves. | we have previously shown that stromal and thylakoid-bound ascorbate peroxidase (apx) isoenzymes of spinach chloroplasts arise from a common pre-mrna by alternative splicing in the c-terminus of the isoenzymes [ishikawa, yoshimura, tamoi, takeda and shigeoka (1997) biochem. j. 328, 795-800]. to explore the production of mature, functional mrna encoding chloroplast apx isoenzymes, reverse transcriptase-mediated pcr and s1 nuclease protection analysis were performed with poly(a)+ rna or polysomal r ... | 1999 | 9931296 |
| presence of a structurally novel type ribulose-bisphosphate carboxylase/oxygenase in the hyperthermophilic archaeon, pyrococcus kodakaraensis kod1. | we have characterized the gene encoding ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) of the hyperthermophilic archaeon, pyrococcus kodakaraensis kod1. the gene encoded a protein consisting of 444 amino acid residues, corresponding in size to the large subunit of previously reported rubiscos. rubisco of p. kodakaraensis kod1 (pk-rubisco) showed only 51.4% similarity with the large subunit of type i rubisco from spinach and 47.3% with that of type ii rubisco from rhodospirillum rubrum ... | 1999 | 9988755 |
| phytoestrogens and human health effects: weighing up the current evidence. | phytoestrogens are naturally occurring plant compounds which have oestrogenic and/or anti-oestrogenic activity. they are present in many human foodstuffs including beans, sprouts, cabbage, spinach, soyabean, grains and hops. the main classes are the isoflavones, coumestans and lignans. this review assesses the evidence that these substances may have adverse and/or beneficial impacts on the risk of several hormone-dependent diseases in humans. evidence from studies of various animal species has d ... | 1998 | 9888630 |
| clp protease complexes and their diversity in chloroplasts. | the clp proteases represent a large, ancient atp-dependent protease family which in higher plants is known to be located in chloroplasts. the soluble, presumably multisubunit, enzyme of the organelle stroma is of dual genetic origin. it consists of a nuclear-encoded, regulatory subunit clpc, which is an atpase, and a plastid-encoded proteolytic subunit clpp, which is a serine protease. an additional, nuclear-encoded proteolytic subunit resembling clpp has been recently reported from tomato (scha ... | 1998 | 9951729 |
| organellar and cytosolic localization of four phosphoribosyl diphosphate synthase isozymes in spinach. | four cdnas encoding phosphoribosyl diphosphate (prpp) synthase were isolated from a spinach (spinacia oleracea) cdna library by complementation of an escherichia coli deltaprs mutation. the four gene products produced prpp in vitro from atp and ribose-5-phosphate. two of the enzymes (isozymes 1 and 2) required inorganic phosphate for activity, whereas the others were phosphate independent. prpp synthase isozymes 2 and 3 contained 76 and 87 amino acid extensions, respectively, at their n-terminal ... | 1999 | 9952445 |
| investigation of the role of surface residues in the ferredoxin from clostridium pasteurianum. | eleven mutant forms of the ferredoxin from clostridium pasteurianum (cpfd; 2 fe4s4; 6200 da) have been isolated in which six surface carboxylates are changed systematically to their uncharged but stereochemically equivalent carboxamide analogues. such changes provide molecules which vary in overall charge and its surface distribution but vary minimally in structure and reduction potential. glu-17 and asp-6, -27, -33, -35, and -39 were converted providing six single mutants, four double mutants a ... | 1999 | 9989216 |
| expression of alfalfa mosaic virus coat protein in tobacco mosaic virus (tmv) deficient in the production of its native coat protein supports long-distance movement of a chimeric tmv. | alfalfa mosaic virus (almv) coat protein is involved in systemic infection of host plants, and a specific mutation in this gene prevents the virus from moving into the upper uninoculated leaves. the coat protein also is required for different viral functions during early and late infection. to study the role of the coat protein in long-distance movement of almv independent of other vital functions during virus infection, we cloned the gene encoding the coat protein of almv into a tobacco mosaic ... | 1999 | 10051680 |
| cdna sequence and overexpression of chloroplast chaperonin 21 from arabidopsis thaliana. | higher plant chloroplasts contain a 21-kda protein, chaperonin 21 (cpn21), that is a functional homolog of the chaperonin 10 (cpn10). the chloroplast cpn21 polypeptide consists of two cpn10-like domains fused together in tandem. we describe here the cdna sequence of the cpn21 (atcpn21) precursor protein from arabidopsis thaliana. the deduced amino acid sequence of the atcpn21 precursor protein, 253 amino acids long, shows 61% identity with the spinach cpn21 protein. the atcpn21 precursor protein ... | 1999 | 9989238 |
| an electron spin-echo envelope modulation (eseem) study of the qa binding pocket of ps ii reaction centers from spinach and synechocystis. | we have used electron spin-echo envelope modulation spectroscopy (eseem) to characterize the protein-cofactor interactions present in the qa- binding pocket of ps ii centers isolated from spinach and synechocystis. we conclude that the eseem spectrum of qa- is the result of interactions of the s = 1/2 electron spin of qa- with the i = 1 nuclear spins of the peptide nitrogens of two different amino acids. one peptide nitrogen has eseem peaks near 0.7, 2.0, 2.85, and 5.0 mhz with isotropic and dip ... | 1999 | 10026288 |
| incision at nucleotide insertions/deletions and base pair mismatches by the sp nuclease of spinach. | spinach leaves contain a highly active nuclease called sp. the purified enzyme incises single-stranded dna, rna, and double-stranded dna that has been destabilized by a-t-rich regions and dna lesions [strickland et al. (1991) biochemistry 30, 9749-9756]. this broad range of activity has suggested that sp may be similar to a family of nucleases represented by s1, p1, and the mung bean nuclease. however, unlike these single-stranded nucleases that require acidic ph and low ionic strength condition ... | 1999 | 10026304 |
| spinach holo-acyl carrier protein: overproduction and phosphopantetheinylation in escherichia coli bl21(de3), in vitro acylation, and enzymatic desaturation of histidine-tagged isoform i. | spinach acp isoform i was overexpressed in escherichia coli bl21(de3) using a gene synthesized from codons associated with high-level expression in e. coli. the synthetic gene has extensive changes in codon usage (23 of 77 total codons) relative to that of the originally synthesized plant gene (p. d. beremand et al., 1987, arch. biochem. biophys. 256, 90-100). after expression of the new synthetic gene, purified acp and acp-his6 were obtained in yields of up to 70 mg l-1 of culture medium, compa ... | 1999 | 10092491 |
| site-directed mutagenesis of serine 158 demonstrates its role in spinach leaf sucrose-phosphate synthase modulation. | site-directed mutagenesis of spinach sucrose-phosphate synthase (sps) was performed to investigate the role of ser158 in the modulation of spinach leaf sps. tobacco plants expressing the spinach wild-type (wt), s158a, s158t and s157f/s158e sps transgenes were produced. expression of transgenes appeared not to reduce expression of the tobacco host sps. sps activity in the wt and the s158t sps transgenics showed light/dark modulation, whereas the s158a and s157f/s158e mutants were not similarly li ... | 1999 | 10205897 |
| mrna degradation. a tale of poly(a) and multiprotein machines. | the escherichia coli rna degradosome is a multiprotein complex containing an endoribonuclease, polynucleotide phosphorylase and a dead-box rna helicase. a related complex has been described in the spinach chloroplast. the exosome and the mtexo complex have recently been described in yeast and it is likely that related complexes also exist in animal cells. this research suggests the widespread existence of sophisticated machines for the efficient degradation of messenger rna. the dead-box helicas ... | 1999 | 10087930 |
| deuteration effects on the in vivo epr spectrum of the reduced secondary photosystem i electron acceptor a1 in cyanobacteria. | the photoreduction of the secondary psi electron acceptor a1 in vivo has recently been detected via x-band epr spectroscopy in intact spinach chloroplasts and in marine cyanobacteria synechococcus pcc 7002 [klughammer, c., and pace, r. j. (1997) biochim. biophys. acta 1318, 133-144]. a further study of the a1- epr spectrum of synechococcus pcc 7002 at room temperature with higher-field resolution revealed partially resolved hyperfine structure which was dominated by 0.4 mt splittings of three eq ... | 1999 | 10090761 |
| plant ribosome recycling factor homologue is a chloroplastic protein and is bactericidal in escherichia coli carrying temperature-sensitive ribosome recycling factor. | we have isolated a protein, mature rrfhcp, from chloroplasts of spinach (spinacia oleracea l.) that shows 46% sequence identity and 66% sequence homology with ribosome recycling factor (rrf) of escherichia coli. rrf recycles ribosomes through disassembly of the posttermination complex. from the cdna analysis and from the amino-terminal sequencing of the isolated protein, the mature rrfhcp was deduced to have a mr of 21,838 with 193 aa. it lacks the 78-aa chloroplast targeting sequence encoded by ... | 1999 | 10318906 |
| genetic analysis of large-sized rna 2 species of a tcm-like tobacco rattle virus source from spinach. | rna 2 of a tobacco rattle virus isolate from spinach (trv sp) resembles that of a recently described isolate from onion (trv on), but its orf 3 is much larger. naturally infected spinach apparently contains a second trv sp rna 2 species with a partially deleted orf 3 and an rna 1-like 3'-end which consists of c. 1500 nts and thus is much longer than in any other tobravirus rna 2 sequenced so far. rnas 2 of trv sp and on are closely related to that of trv tcm from tulip, but besides the additiona ... | 1999 | 10226616 |
| response to high-pressure, low-temperature treatment in vegetables: determination of survival rates of microbial populations using flow cytometry and detection of peroxidase activity using confocal microscopy. | application of high hydrostatic pressure (200, 300, 350 and 400 mpa) at 5 degrees c for 30 min to different micro-organisms, including gram-positive and gram-negative bacteria, moulds and yeasts, proved to be more effective in inactivating these organisms than treatments at 20 degrees c for 10 min and at 10 degrees c for 20 min. moulds, yeasts, gram-negative bacteria and listeria monocytogenes were most sensitive, and their populations were completely inactivated at pressures between 300 and 350 ... | 1999 | 10196760 |
| two snf1-related protein kinases from spinach leaf phosphorylate and inactivate 3-hydroxy-3-methylglutaryl-coenzyme a reductase, nitrate reductase, and sucrose phosphate synthase in vitro. | we resolved from spinach (spinacia oleracea) leaf extracts four ca2+-independent protein kinase activities that phosphorylate the amaraasaaalarrr (amara) and hmrsamsglhlvkrr (sams) peptides, originally designed as specific substrates for mammalian amp-activated protein kinase and its yeast homolog, snf1. the two major activities, hrk-a and hrk-c (3-hydroxy-3-methylglutaryl-coenzyme a reductase kinase a and c) were extensively purified and shown to be members of the plant snrk1 (snf1-related prot ... | 1999 | 10318703 |
| isolation and characterization of the gene encoding the starch debranching enzyme limit dextrinase from germinating barley. | the gene encoding the starch debranching enzyme limit dextrinase, ld, from barley (hordeum vulgare), was isolated from a genomic phage library using a barley cdna clone as probe. the gene encodes a protein of 904 amino acid residues with a calculated molecular mass of 98.6 kda. this is in agreement with a value of 105 kda estimated by sds-page. the coding sequence is interrupted by 26 introns varying in length from 93 bp to 825 bp. the 27 exons vary in length from 53 bp to 197 bp. southern blot ... | 1999 | 10350630 |
| heterologous overexpression of membrane-anchored subunit ii of spinach chloroplast atp synthase and its detergent-free purification as a soluble protein. | subunit ii is one of the four nonidentical subunits of the membrane integral, proton-transporting moiety (cfo) of the chloroplast atp synthase. in chloroplasts of spinach leaves, it is the only nuclear-encoded cfo subunit. it has been deduced that cfoii is not an additional subunit typical for photosynthetic organisms with no counterpart in e. coli, but equivalent to e. coli subunit b (tiburzy, h.-j. and berzborn, r. j. (1997), z. naturforsch. 52c, 789-798). heterologous expression of subunit ii ... | 1999 | 10349741 |
| not enough spinach? | | 1998 | 10408929 |
| [effect of green vegetable on digestive tract absorption of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in rats]. | the effect green vegetable on fecal excretion of polychlorinated dibenzo-p-dioxin (pcdd) congeners and polychlorinated dibenzofuran (pcdf) congeners was examined in male rats. the rats were administered 10% vegetable diets or a basal diet containing 0.2 ml of the causal rice-bran oil of yusho that had occurred in the southwest part of japan in 1968 and kept on the same diet for five days. the fecal excretion of 2,3,7,8-t4cdd and 2,3,4,7,8-p5cdf in the group fed with komatsuna, mitsuba, spinach a ... | 1999 | 10396873 |
| comparison of phylloquinone bioavailability from food sources or a supplement in human subjects. | phylloquinone (k) absorption was assessed in 22- to 30-y-old human subjects consuming a standard test meal [402 kcal (1682 kj), 27% energy from fat]. the absorption of phylloquinone, measured over a 9-h period as the area under the curve (auc), was higher (p < 0.01) after the consumption of a 500- microgram phylloquinone tablet [27.55 +/- 10.08 nmol/(l. h), n = 8] than after the ingestion of 495 microgram phylloquinone as 150 g of raw spinach [4.79 +/- 1.11 nmol/(l. h), n = 3]. less phylloquinon ... | 1999 | 10356087 |
| hyperoxia-induced changes in antioxidant capacity and the effect of dietary antioxidants. | we investigated, by measuring oxygen radical absorbance capacity (orac), whether hyperoxia causes alterations in antioxidant status and whether these alterations could be modulated by dietary antioxidants. rats were fed for 8 wk a control diet or a control diet supplemented with vitamin e (500 iu/kg) or with aqueous extracts (orac: 1.36 mmol trolox equivalents/kg) from blueberries or spinach and then were exposed to air or >99% o2 for 48 h. although the constituents of the extracts were not exte ... | 1999 | 10368343 |
| mössbauer and electron paramagnetic resonance studies of the cytochrome bf complex. | the (57)fe-enriched cytochrome bf complex has been isolated from hydrocultures of spinach. it has been studied at different redox states by optical, epr, and mössbauer spectroscopy. the mössbauer spectrum of the native complex at 190 k with all iron centers in the oxidized state reveals the presence of four different iron sites: low-spin ferric iron in cytochrome b [with an isomer shift (delta) of 0.20 mm/s, a quadrupole splitting (deltae(q)) of 1.77 mm/s, and a relative area of 40%], low-spin f ... | 1999 | 10413471 |
| mechanism of light regulation of rubisco: a specific role for the larger rubisco activase isoform involving reductive activation by thioredoxin-f. | rubisco activase is a nuclear-encoded chloroplast protein that is required for the light activation of ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) in vivo. in most plants examined to date, there are two isoforms of rubisco activase arising from alternative splicing that differ only at the carboxyl terminus. here we demonstrate with recombinant proteins that in arabidopsis the larger isoform has a unique role in the regulation of rubisco activity. at physiological ratios of adp/atp, ... | 1999 | 10430961 |
| structure of a histidine ligand in the photosynthetic oxygen-evolving complex as studied by light-induced fourier transform infrared difference spectroscopy. | fourier transform infrared (ftir) signals of a histidine side chain were identified in flash-induced s(2)/s(1) difference spectra of the oxygen-evolving complex (oec) of photosystem ii (ps ii) using ps ii membranes from globally (15)n-labeled spinach and ps ii core complexes from synechocystis cells in which both the imidazole nitrogens of histidine were selectively labeled with (15)n. a negative band at 1113-1114 cm(-1) was downshifted by 7 cm(-1) upon both global (15)n-labeling and selective [ ... | 1999 | 10433727 |
| interaction of the soluble recombinant psad subunit of spinach photosystem i with ferredoxin i. | photosystem i of higher plants functions in photosynthesis as a light-driven oxidoreductase producing reduced ferredoxin. its peripheral subunit psad has been identified as the docking site for ferredoxin i. with the aim of elucidating the structure-function relationship and the role of this subunit, a recombinant form of the spinach protein was produced by heterologous expression in escherichia coli. the psad protein was synthesized in soluble form and purified to homogeneity. the interaction o ... | 1999 | 10451365 |
| molecular characterization of ribulose-1,5-bisphosphate carboxylase/oxygenase activase in rice leaves. | a full-length cdna (designated rcaii) encoding the rubisco activase (rca) of rice (oryza sativa l.) has been cloned from a cdna library constructed with mrna from green leaves. sequence analysis resulted in a reading frame of 432 amino acids with a calculated molecular mass of 47.9 kda and an estimated isoelectric point of 5.97. the deduced amino acid sequence showed 74-89% identity with other rubisco activases from higher plants. two highly conserved motifs were identified. southern blot analys ... | 1999 | 10467032 |
| a productive nadp+ binding mode of ferredoxin-nadp + reductase revealed by protein engineering and crystallographic studies. | the flavoenzyme ferredoxin-nadp+ reductase (fnr) catalyzes the production of nadph during photosynthesis. whereas the structures of fnrs from spinach leaf and a cyanobacterium as well as many of their homologs have been solved, none of these studies has yielded a productive geometry of the flavin-nicotinamide interaction. here, we show that this failure occurs because nicotinamide binding to wild type fnr involves the energetically unfavorable displacement of the c-terminal tyr side chain. we us ... | 1999 | 10467097 |
| plant riboflavin biosynthesis. cloning, chloroplast localization, expression, purification, and partial characterization of spinach lumazine synthase. | lumazine synthase, which catalyzes the penultimate step of riboflavin biosynthesis, has been cloned from three higher plants (spinach, tobacco, and arabidopsis) through functional complementation of an escherichia coli auxotroph. whereas the three plant proteins exhibit some structural similarities to known microbial homologs, they uniquely possess n-terminal polypeptide extensions that resemble typical chloroplast transit peptides. in vitro protein import assays with intact chloroplasts and imm ... | 1999 | 10419541 |
| overexpression in escherichia coli and characterization of the chloroplast triosephosphate isomerase from spinach. | an important calvin cycle enzyme, chloroplast triosephosphate isomerase (cptpi) from spinach, has been cloned and expressed in up to 15% of the total cell protein using the p(l) expression vector in escherichia coli. an even higher level expression, up to 36% of the total protein, was achieved by replacing the nucleotide sequence between the ribosomal binding site and the initial codon, atg, with an at-rich sequence. computer modeling revealed that the moderate change in the standard free energy ... | 1999 | 10425165 |
| structure of l-aspartate oxidase: implications for the succinate dehydrogenase/fumarate reductase oxidoreductase family. | given the vital role of nad+ in cell metabolism, the enzymes involved in bacterial de novo nad+ biosynthesis are possible targets for drug design against pathogenic bacteria. the first reaction in the pathway is catalysed by l-aspartate oxidase (laspo), a flavoenzyme that converts aspartate to iminoaspartate using either molecular oxygen or fumarate as electron acceptors. laspo has considerable sequence homology with the flavoprotein subunits of succinate dehydrogenase (sdh) and fumarate reducta ... | 1999 | 10425677 |
| reversals of age-related declines in neuronal signal transduction, cognitive, and motor behavioral deficits with blueberry, spinach, or strawberry dietary supplementation. | ample research indicates that age-related neuronal-behavioral decrements are the result of oxidative stress that may be ameliorated by antioxidants. our previous study had shown that rats given dietary supplements of fruit and vegetable extracts with high antioxidant activity for 8 months beginning at 6 months of age retarded age-related declines in neuronal and cognitive function. the present study showed that such supplements (strawberry, spinach, or blueberry at 14.8, 9.1, or 18.6 gm of dried ... | 1999 | 10479711 |
| a highly active, soluble mutant of the membrane-associated (s)-mandelate dehydrogenase from pseudomonas putida. | (s)-mandelate dehydrogenase (mdh) from pseudomonas putida, a member of the flavin mononucleotide-dependent alpha-hydroxy acid oxidase/dehydrogenase family, is a membrane-associated protein, in contrast to the more well-characterized members of this protein family including glycolate oxidase (gox) from spinach. in a previous study [mitra, b., et al. (1993) biochemistry 32, 12959-12967], the membrane association of mdh was correlated to a 53 amino acid segment in the interior of the primary sequen ... | 1999 | 10493804 |
| a prospective study of carotenoid intake and risk of cataract extraction in us men. | dietary antioxidants, including carotenoids, are hypothesized to decrease the risk of age-related cataracts by preventing oxidation of proteins or lipids within the lens. however, prospective epidemiologic data concerning this phenomenon are limited. | 1999 | 10500021 |
| kinetic evidence for the psae-dependent transient ternary complex photosystem i/ferredoxin/ferredoxin:nadp(+) reductase in a cyanobacterium. | a mutant of synechocystis pcc 6803, deficient in psae, assembles photosystem i reaction centers without the psae subunit. under conditions of acceptor-side rate-limited photoreduction assays in vitro (with 15 microm plastocyanin included), using 100 nm ferredoxin:nadp(+) reductase (fnr) and either synechocystis flavodoxin or spinach ferredoxin, lower rates of nadp(+) photoreduction were measured when psae-deficient membranes were used, as compared to the wild type. this effect of the psae mutati ... | 1999 | 10504244 |
| bacteriological investigation of an outbreak of clostridium perfringens food poisoning caused by japanese food without animal protein. | an outbreak of clostridium perfringens food poisoning occurred in a senior citizen's home in japan. japanese food, spinach boiled with fried bean curd, was considered to be the causative food as a result of the detection of the c. perfringens enterotoxin gene by nested pcr. the number of enterotoxin-positive c. perfringens was enumerated as 4.3 x 10(5)/g in the causative food by the mpn method combined with nested pcr. by cultivation, enterotoxin-positive c. perfringens was isolated from all the ... | 1999 | 10477076 |
| in vivo and in vitro phosphorylation of rice dwarf phytoreovirus pns12 cytoplasmic nonstructural protein. | in vivo and in vitro phosphorylation and intracellular location of rice dwarf phytoreovirus pns12, which is encoded by one of the twelve dsrna genome segments, s12, and comprises 312 amino acids, was investigated. when [32p]phosphoric acid was incorporated into rdv-infected leafhopper cultured cells, labelled pns12 was immunoprecipitated from the cells by a monospecific anti-pns12 polyclonal antibody. recombinant pns12 was purified from spodoptera frugiperda cells infected with acrs12, a baculov ... | 1999 | 10481743 |
| regulation of spinach snf1-related (snrk1) kinases by protein kinases and phosphatases is associated with phosphorylation of the t loop and is regulated by 5'-amp. | members of the snf1-related protein kinase-1 (snrk1) subfamily of protein kinases are higher plant homologues of mammalian amp-activated and yeast snf1 protein kinases. based on analogies with the mammalian system, we surmised that the snrk1 kinases would be regulated by phosphorylation on a threonine [equivalent to thr175 in arabidopsis thaliana snrk1 (akin10)] within the 't loop' between the conserved dfg and ape motifs. we have raised an antibody against a phosphopeptide based on this sequenc ... | 1999 | 10504565 |
| biochemical and topological properties of type a mgdg synthase, a spinach chloroplast envelope enzyme catalyzing the synthesis of both prokaryotic and eukaryotic mgdg. | mgdg synthase, the enzyme that catalyzes the synthesis of the major chloroplast membrane lipid monogalactosyldiacylglycerol (mgdg), is encoded by a multigenic family. we have analyzed the biochemical properties, subcellular localization and membrane topology of a spinach chloroplast mgdg synthase, a representative member of the type a family from spinacia oleracea (somgd a), using a recombinant protein that was functionally overexpressed in escherichia coli and specific polyclonal antibodies. we ... | 1999 | 10518794 |
| related alphan- and epsilonn-methyltransferases methylate the large and small subunits of rubisco. | ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) is methylated at the ax amino position of the n-terminal methionyl residue of the processed and assembled form of the small subunit (ss), and is also methylated in some species at the epsilon-amino group of lysine-14 in the large subunit (ls). the gene (rbcmt-s) and cdnas for the ss alphan-methyltransferase (ssmt) from spinach (spinach oleracea) have been cloned, sequenced, and expressed. the gene is closely related to a previously charac ... | 1998 | 10526959 |
| an electrochemical study of the factors responsible for modulating the reduction potential of putidaredoxin. | the gene coding for putidaredoxin has been synthesized using a combination of chemical and enzymatic methods and subsequently expressed in escherichia coli. the recombinant protein characterized by electronic spectroscopy, mass spectrometry, and electrochemistry was found to be identical to putidaredoxin obtained from pseudomonas putida. polylysine was found to promote the fast and reversible electrochemistry of putidaredoxin at negatively charged electrodes such as indium-doped tin oxide or gol ... | 1999 | 10550696 |
| a difference fourier transform infrared study of tyrosyl radical z* decay in photosystem ii. | photosystem ii (psii) contains a redox-active tyrosine, z* difference fourier transform infrared (ftir) spectroscopy can be used to obtain structural information about this species, which is a neutral radical, z*, in the photooxidized form. previously, we have used isotopic labeling, inhibitors, and site-directed mutagenesis to assign a vibrational line at 1478 cm(-1) to z*; these studies were performed on highly resolved psii preparations at ph 7.5, under conditions where q(a)(-) and q(b)(-) ma ... | 1999 | 10512833 |
| development of an in vitro digestion method to assess carotenoid bioavailability from meals. | the objective of this study was to develop a model for assessing the bioavailability of carotenoids from meals using an in vitro digestion procedure. a meal was prepared using baby food carrots, spinach, and a meat, plus tomato paste. the aqueous fraction was isolated from digesta to determine the quantity of carotenoids transferred from the food to micelles. the micellarization of lutein (25-40%) exceeded (p < 0.01) that of alpha- and beta-carotene (12-18%) and lycopene (<0.5%). micellarization ... | 1999 | 10552806 |
| a market basket survey of inorganic arsenic in food. | dietary arsenic intake estimates based on surveys of total arsenic concentrations appear to be dominated by intake of the relatively non-toxic, organic arsenic forms found in seafood. concentrations of inorganic arsenic in food have not been not well characterized. accurate dietary intake estimates for inorganic arsenic are needed to support studies of arsenic's status as an essential nutrient, and to establish background levels of exposure to inorganic arsenic. in the market basket survey repor ... | 1999 | 10506007 |
| determination of epsilon-n-pyrrolylnorleucine in fresh food products. | epsilon-n-pyrrolylnorleucine was determined in different fresh food products to study its presence as a normal component of food proteins. twenty-two different products were screened: cod, cuttlefish, salmon, sardine, trout, beef, chicken, pork, broad bean, broccoli, chickpea, garlic, green pea, lentil, mushroom, soybean, spinach, sunflower, almond, hazelnut, peanut, and walnut. foods were homogenized, their proteins were precipitated with trichloroacetic acid and hydrolyzed with 2 n naoh for 20 ... | 1999 | 10552475 |
| beta-carotene does not change markers of enzymatic and nonenzymatic antioxidant activity in human blood. | in vitamin a-replete populations, increased concentrations of serum carotenoids have been associated with a decreased risk of degenerative diseases. the mechanism of action of carotenoids in determining antioxidant activity is largely unknown. the aim of the study was to examine the effect of carotenoid supplementation and spinach intake on erythrocyte enzyme antioxidant activities, serum or plasma nonenzymatic antioxidant concentrations, and concentrations of oxidatively damaged amino acids in ... | 1999 | 10573544 |
| molecular cloning, expression, and functional characterization of a 2cys-peroxiredoxin in chinese cabbage. | a cdna (c2c-prx) corresponding to a 2cys-peroxiredoxin (2cys-prx) was isolated from a leaf cdna library of chinese cabbage. the predicted amino acid sequence of c2c-prx has 2 conserved cysteines and several peptide domains present in most of the 2cys-prx subfamily members. it shows the highest sequence homology to the 2cys-prx enzymes of spinach (88%) and arabidopsis (86%). southern analysis using the cdna insert of c2c-prx revealed that it consists of a small multigene family in chinese cabbage ... | 1999 | 10487217 |
| effect of vegetable and carotenoid consumption on aberrant crypt multiplicity, a surrogate end-point marker for colorectal cancer in azoxymethane-induced rats. | epidemiological studies indicate that increased vegetable consumption reduces the risk of colorectal cancer mortality. in the present study we have investigated the effect of consumption of standard diets supplemented with freeze-dried vegetables (peas, spinach, sprouts and broccoli) and carotenoids (all-trans beta-carotene and palm oil carotenoid extract) on surrogate end-point markers for colorectal cancer in an azoxymethane-induced rat model. mean aberrant crypt multiplicity was reduced (19%) ... | 1999 | 10590218 |
| rubisco small and large subunit n-methyltransferases. bi- and mono-functional methyltransferases that methylate the small and large subunits of rubisco. | ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco)is methylated at the alpha-amino group of the n-terminal methionine of the processed form of the small subunit (ss), and at the epsilon-amino group of lysine-14 of the large subunit (ls) in some species. the rubisco ls methyltransferase (lsmt) gene has been cloned and expressed from pea and specifically methylates lysine-14 of the ls of rubisco. we determine here that both pea and tobacco rubisco lsmt also exhibit (alpha)n-methyltransferas ... | 1999 | 10593982 |
| the assembly of the caat-box binding complex at a photosynthesis gene promoter is regulated by light, cytokinin, and the stage of the plastids. | a functionally important region in the promoter of the spinach photosynthesis gene atpc, which encodes the subunit gamma of the chloroplast atp synthase, is located immediately upstream of the caat-box. a single nucleotide exchange in this region (aaaattcaat --> aagatcaat) uncouples the expression of an atpc promoter::uida gene fusion from the regulation by light, cytokinin, and functional plastids and results in a high constitutive expression of the reporter gene. by screening an arabidopsis th ... | 1999 | 10585491 |
| a cyclophilin-regulated pp2a-like protein phosphatase in thylakoid membranes of plant chloroplasts. | dephosphorylation of central photosynthetic proteins regulates their turnover in plant thylakoid membranes. a membrane protein phosphatase from spinach thylakoids was purified 13000-fold using detergent-engaged fplc. the purified enzyme exhibited characteristics typical of eukaryotic ser/thr phosphatases of the pp2a family in that it was inhibited by okadaic acid (ic(50) = 0.4 nm) and tautomycin (ic(50) = 25 nm), irreversibly bound to microcystin-agarose, and recognized by a polyclonal antibody ... | 1999 | 10555977 |
| spinach hexokinase i is located in the outer envelope membrane of plastids. | the subcellular localization of hexokinase activities in plant cells has been a matter of debate for a long time. we have isolated a hexokinase cdna fragment from glucose-fed spinach leaves using a differential display reverse transcription-pcr approach. the corresponding cdna was expressed in escherichia coli and an antiserum, raised against the recombinant protein, was used in subcellular localization studies. the spinach hexokinase could be localized primarily to the outer envelope membrane o ... | 1999 | 10561488 |
| genetic dissection of tomato bushy stunt virus p19-protein-mediated host-dependent symptom induction and systemic invasion. | the plus-sense single-stranded rna of tomato bushy stunt virus (tbsv) encodes a 19-kda protein, which is translated from a 3' proximal open reading frame (p19) that is entirely nested within the cell-to-cell movement gene (p22). expression of the cytosolic p19-protein induces either a systemic lethal collapse in nicotiana benthamiana and n. clevelandii, or necrotic local lesions on resistant n. tabacum. in spinach, the p19-protein is required at high abundance for efficient systemic invasion. th ... | 2000 | 10612662 |
| crystal structure analysis of a pentameric fungal and an icosahedral plant lumazine synthase reveals the structural basis for differences in assembly. | lumazine synthase catalyzes the penultimate step in the synthesis of riboflavin in plants, fungi, and microorganisms. the enzyme displays two quaternary structures, the pentameric forms in yeast and fungi and the 60-meric icosahedral capsids in plants and bacteria. to elucidate the structural features that might be responsible for differences in assembly, we have determined the crystal structures of lumazine synthase, complexed with the inhibitor 5-nitroso-6-ribitylamino-2,4-pyrimidinedione, fro ... | 1999 | 10595538 |
| transcripts containing the 5' untranslated regions of the plastid genes psba and psbb from higher plants are unstable in chlamydomonas reinhardtii chloroplasts. | the 5' regions of chloroplast genes contain cis-acting regulatory elements including promoters, and determinants of rna stability and translation. in this work i examined whether the 5' regions of the spinach psbb and the wheat psba genes can drive the expression of an aada reporter gene in chloroplasts of the unicellar green alga chlamydomonas reinhardtii. both plant 5' sequences confer aada-dependent, spectinomycin resistance on escherichia coli, but not on the alga following integration into ... | 1999 | 10628859 |
| hybrid rhodospirillum rubrum f(0)f(1) atp synthases containing spinach chloroplast f(1) beta or alpha and beta subunits reveal the essential role of the alpha subunit in atp synthesis and tentoxin sensitivity. | trace amounts ( approximately 5%) of the chloroplast alpha subunit were found to be absolutely required for effective restoration of catalytic function to licl-treated chromatophores of rhodospirillum rubrum with the chloroplast beta subunit (avital, s., and gromet-elhanan, z. (1991) j. biol. chem. 266, 7067-7072). to clarify the role of the alpha subunit in the rebinding of beta, restoration of catalytic function, and conferral of sensitivity to the chloroplast-specific inhibitor tentoxin, licl ... | 2000 | 10625626 |
| characterization of violaxanthin de-epoxidase purified in the presence of tween 20: effects of dithiothreitol and pepstatin a. | violaxanthin de-epoxidase (vde) was purified from thylakoid membranes of spinach by conventional column chromatography in the presence of tween 20. the neutral detergent was necessary to prevent non-specific interaction of vde with column resins. in anion-exchange chromatography on mono q, vde appeared in two peaks. both peaks exhibited a polypeptide of 41 kda when fully reduced with 5 mm dithiothreitol. re-chromatography of either peak gave rise to both peaks, suggesting that the two forms of v ... | 1999 | 10635115 |
| d-ribose-5-phosphate isomerase from spinach: heterologous overexpression, purification, characterization, and site-directed mutagenesis of the recombinant enzyme. | a cdna encoding spinach chloroplastic ribose-5-phosphate isomerase (rpi) was cloned and overexpressed in escherichia coli, and a purification scheme for the recombinant enzyme was developed. the purified recombinant rpi is a homodimer of 25-kda subunits and shows kinetic properties similar to those of the homodimeric enzyme isolated from spinach leaves (a. c. rutner, 1970, biochemistry 9, 178-184). phosphate, used as a buffer in previous studies, is a competitive inhibitor of rpi with a k(i) of ... | 2000 | 10620366 |
| electrometrical study of electron transfer from the terminal fa/fb iron-sulfur clusters to external acceptors in photosystem i. | an electrometrical technique was used to investigate electron transfer between the terminal iron-sulfur centers f(a)/f(b) and external electron acceptors in photosystem i (ps i) complexes from the cyanobacterium synechococcus sp. pcc 6301 and from spinach. the increase of the relative contribution of the slow components of the membrane potential decay kinetics in the presence of both native (ferredoxin, flavodoxin) and artificial (methyl viologen) electron acceptors indicate the effective intera ... | 1999 | 10622738 |
| effects of aging on cerebellar noradrenergic function and motor learning: nutritional interventions. | aging is associated with a decline in motor coordination and the ability to learn new motor learning skills. this loss of function is correlated with a decline in cerebellar beta-adrenergic receptor function. we have examined the role of oxidative stress on this system by exposing young rats to normobaric hyperoxia. this exogenous oxidative insult results in a decline in cerebellar beta-adrenergic receptor function that resembles what is observed in normal aged rats. this effect of hyperoxia is ... | 1999 | 10656533 |
| the topology of phosphatidylglycerol populations is essential for sustaining photosynthetic electron flow activities in thylakoid membranes. | the transmembrane distribution of phosphatidylglycerol (pg) was determined in rightside-out (ro) and inside-out vesicles (io) obtained by fragmentation of spinach thylakoids in a yeda press, followed by partition in an aqueous dextran-polyethyleneglycol two-phase system. using the phospholipase a(2) from porcine pancreas to digest selectively pg molecules in the outer monolayer (exposed to the incubation medium) of the membrane, we found the molar outside/inside distribution to be 70/30+/-5 in r ... | 2000 | 10631300 |
| update from asia. asian studies on cancer chemoprevention. | in asia, nontoxic dietary products are considered desirable primary prevention vehicles for conquering cancer. as early as 1978, investigators in korea carried out extensive long-term anticarcinogenicity experiments using the mouse lung tumor model and observed an anticarcinogenic effect of panax ginseng c.a. meyer extract in 1980. the results showed that natural products can provide hope for human cancer prevention. a newly established nine-week medium-term model using mouse lung tumors (yun's ... | 1999 | 10668493 |
| 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 |