| the epsilon subunit of the chloroplast coupling factor 1 from euglena gracilis: a possible role in controlling atpase activity. | the coupling factor from chloroplasts (cf(1)) of euglena gracilis z strain is an active atpase in situ, and its activity cannot be increased by treatment with trypsin or heating as is the case with the cf(1) from other sources. the smallest subunit of cf(1), the epsilon subunit, is supposed to be involved in controlling the atpase activity. we have devised a simple technique for rapid and large-scale isolation of this subunit. the epsilon subunit from euglena cf(1), although having only a limite ... | 1982 | 16662514 |
| thylakoid polypeptides of light and dark aged chloroplasts. | spinach (spinacia oleracea) chloroplasts were aged at 4 degrees c under red light and in the dark. the electron transport activity was monitored together with the thylakoid polypeptide patterns in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. the light-induced decay of photosystem ii (psii) activity (half-life, about 4 hours) was correlated with a decrease in polypeptides with apparent molecular weights of 36, 48, and 50 kilodaltons. there was very little decay of photosystem i (psi ... | 1982 | 16662578 |
| mode of action of a herbicide : johnsongrass and methanearsonic acid. | johnsongrass (sorghum halepense (l.) pers.) is sensitive to methanearsonate, foliar application resulting in a topkill. investigation of the pattern of photosynthesis by radioautography revealed an accumulation of malate in methanearsonate-treated leaves. accumulation of malate was attributed to an inhibition of nadp(+)-malic enzyme which was found to be sensitive to sulfhydryl group reagents including arsenosomethane, ch(3)aso. methanearsonate was found to act as an oxidant in the hill reaction ... | 1983 | 16662810 |
| effects of photosystem ii herbicides on the photosynthetic membranes of the cyanobacterium aphanocapsa 6308. | the effects of the photosystem ii herbicides diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) and atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) on the photosynthetic membranes of a cyanobacterium, aphanocapsa 6308, were compared to the effects on a higher plant, spinacia oleracea. the inhibition of photosystem ii electron transport by these herbicides was investigated by measuring the photoreduction of the dye 2,6-dichlorophenol-indophenol spectrophotometrically using isolated mem ... | 1983 | 16662835 |
| stromal acidification mediates in vivo water stress inhibition of nonstomatal-controlled photosynthesis. | stromal acidification has been reported to mediate reduced osmotic potential (psi(pi)) effects on photosynthesis in the isolated spinach chloroplast (berkowitz, gibbs 1983 plant physiol 72: 1100-1109). to determine if stromal acidification mediates osmotic dehydration inhibition of photosynthesis in vivo, the effects of a weak base (nh(4)cl), which raises stromal ph, on co(2) fixation of vacuum-infiltrated spinach leaf slices, chlamydomonas reinhardii cells and aphanocapsa 6308 cells under isoto ... | 1983 | 16663131 |
| distribution of calmodulin-stimulated ca transport into membrane vesicles from green spinach leaves. | a microsomal fraction isolated from green spinach leaves exhibited a mg(2+) and atp-dependent (45)ca(2+) uptake. addition of 10 micromolar carbonyl cyanide m-chlorophenylhydrazine had no effect. the cationophore a23187 (10 micromolar) induced the release of (45)ca(2+) accumulated by membrane vesicles. membranes prepared from lower epidermis showed the highest ca(2+) accumulation activity. microsomal fractions from petiole, lamina, and midrib were less active. the stimulation by bovine brain calm ... | 1983 | 16663135 |
| spinach leaf intra and extra chloroplast phosphorylase activities during growth. | the amino terminal sequence of the spinach (spinacia oleracea l. cv bloomsdale long standing) leaf cytoplasmic phosphorylase was determined and shown to have little similarity to the known sequence of the potato tuber phosphorylase. the antigenic reaction of spinach chloroplast phosphorylase and rabbit muscle phosphorylase a to antiserum prepared against spinach leaf cytoplasmic phosphorylase was tested. neither phosphorylase gave a positive reaction when tested by immunodiffusion or neutralizat ... | 1983 | 16663287 |
| atp-dependent proteolytic activity from spinach leaves. | spinach (spinacia oleracea cv bloomsdale long standing) leaf cytoplasmic starch phosphorylase and rabbit muscle phosphorylase a were inactivated by incubation with partially purified leaf extract in the presence of atp and mg(2+). the inactivating factor(s) were heat stable and susceptible to protease attack. phosphorylase inactivation was prevented by incubation in the presence of p-aminobenzamidine and phenylboronic acid, or prolonged treatment with phenylmethylsulfonyl fluoride or leupeptin f ... | 1983 | 16663340 |
| use of zinc ions to study thylakoid protein phosphorylation and the state 1-state 2 transition in vitro. | at atp concentrations less than 0.2 millimolar, zinc ions cause a marked stimulation of endogenous protein phosphorylation in thylakoid membranes isolated from tobacco (nicotiana tabacum l. cv turkish samsun), pea (pisum sativum l. cv feltham first) and spinach (spinacia oleracea l. cv northland). the greatest stimulatory effect was observed at zn(2+) concentrations of 1 to 2 millimolar; higher concentrations were inhibitory. the stimulatory effect of zn(2+) was independent of mg(2+) concentrati ... | 1984 | 16663421 |
| control of lipid synthesis during soybean seed development: enzymic and immunochemical assay of acyl carrier protein. | during soybean seed (glycine max, var am soy 71) development, the rate of lipid biosynthesis per seed increases greatly. as the seed reaches maturity, lipid synthesis declines. to study the controls over the oil synthesis and storage process, we have chosen acyl carrier protein (acp) as a representative marker for the fatty acid synthetase pathway. we have quantitated soybean acp levels by both enzymic and immunochemical methods. escherichia coli acyl-acp synthetase was used as an assay for enzy ... | 1984 | 16663471 |
| purification and comparative characterization of an enolase from spinach. | an enolase has been purified to apparent homogeneity, as measured by gel electrophoresis, some 400-fold from spinach (spinacia oleracea). this is the first plant enolase that has been purified to homogeneity. at moderate ionic strengths, the 5,5-dithio-bis-2-(nitrobenzoate) (dtnb)-or parachloromercuribenzoate-reacted enzyme elutes from a bio-gel p-200 column with somewhat greater volumes than the yeast enzyme (m(r) = 93,000) indicating a greater size. its elution volume from ultrogel in 50% ammo ... | 1984 | 16663518 |
| rates and products of long-chain fatty acid synthesis from [1-c]acetate in chloroplasts isolated from leaves of 16:3 and 18:3 plants. | chloroplasts highly active in the synthesis of long-chain fatty acids from [1-(14)c]acetate were prepared from leaves of solanum nodiflorum, chenopodium quinoa, carthamus tinctorius, and pisum sativum. these preparations were used to test whether the various additions to incubation media found to stimulate the synthesis of particular lipid classes in vitro by spinacia oleracea chloroplasts were applicable generally. chloroplasts from 18:3 plants incorporated a greater proportion of radioactivity ... | 1984 | 16663528 |
| pyruvate orthophosphate dikinase of c(3) seeds and leaves as compared to the enzyme from maize. | pyruvate orthophosphate dikinase (ppdk) was found in various immature seeds of c(3) plants (wheat, pea, green bean, plum, and castor bean), in some c(3) leaves (tobacco, spinach, sunflower, and wheat), and in c(4) (maize) kernels. the enzyme in the c(3) plants cross-reacts with rabbit antiserum against maize ppdk. based on protein blot analysis, the apparent subunit size of ppdk from wheat seeds and leaves and from sunflower leaves is about 94 kdaltons, the same as that of the enzyme from maize, ... | 1984 | 16663632 |
| kinetic variance of ribulose-1,5-bisphosphate carboxylase/oxygenase isolated from diverse taxonomic sources : ii. analysis by two dual label methods. | two dual label methods were used to investigate kinetic variability of ribulose 1,5-bisphosphate (rubp) carboxylase/oxygenase (ec 4.1.1.39). in addition to using [1-(14)c,5-(3)h]rubp (method 1), we describe here the detailed assay with (14)co(2) and [5-(3)h]rubp (method 2), which generates [(3)h,(14)c]3-phosphoglyceric acid and unlabeled (noncontaminating) phosphoglycolate; the carboxylase/oxygenase activity ratio (v(c)/v(o)) is calculated from (3)h/(14)c ratios of substrates and products. v(c)/ ... | 1984 | 16663680 |
| partitioning of nitrogen among ribulose-1,5-bisphosphate carboxylase/oxygenase, phosphoenolpyruvate carboxylase, and pyruvate orthophosphate dikinase as related to biomass productivity in maize seedlings. | maize (zea mays l. cv golden cross bantam t51) seedlings were grown under full sunlight or 50% sunlight in a temperature-controlled glasshouse at the temperatures of near optimum (30/25 degrees c) and suboptimum (17/13 degrees c) with seven levels of nitrate-n (0.4 to 12 millimolars). the contents of phosphoenolpyruvate carboxylase (pepc), pyruvate orthophosphate dikinase (ppd), and ribulose-1,5-p(2) carboxylase/oxygenase (rubisco) were immunochemically determined for each treatment with rabbit ... | 1984 | 16663684 |
| structural characterization of a higher plant calmodulin : spinacia oleracea. | calmodulin is a eukaryotic calcium binding protein which has several calcium-dependent in vitro activities. presented in this report is a structural characterization of calmodulin from spinach leaves (spinacia oleracea). spinach calmodulin may be representative of higher plant calmodulins in general since calmodulin from the monocotyledon barley (hordeum vulgare) is indistinguishable by a variety of physical, chemical, and functional criteria (schleicher, lukas, watterson 1983 plant physiol 73: ... | 1984 | 16663705 |
| comparison of the nad kinase and myosin light chain kinase activator properties of vertebrate, higher plant, and algal calmodulins. | in the preceding paper (lukas, iverson, schleicher, watterson 1984 plant physiol 75: 788-795), we reported that the amino acid sequence of spinach calmodulin has at least 13 amino acid sequence differences from vertebrate calmodulin. in the present study, we investigated the effect of these amino acid sequence substitutions on the enzyme activator properties of vertebrate and plant calmodulins. calmodulins from spinach and the green alga chlamydomonas reinhardtii activate chicken gizzard myosin ... | 1984 | 16663706 |
| ribulose bisphosphate carboxylase/oxygenase content determined with [c]carboxypentitol bisphosphate in plants and algae. | as is the case with spinach ribulose bisphosphate carboxylase/oxygenase (rubisco), [(14)c]carboxyarabinitol bisphosphate (cabp) bound to purified chlorella rubisco with a molar ratio of unity to large subunit of the enzyme. the concentration of binding sites in extracts of photosynthetic organisms was determined by reacting the extracts with [(14)c]-carboxypentitol bisphosphate (cpbp) and precipitating the resultant rubisco-[(14)c]cabp complex with a combination of polyethylene glycol-4000 and m ... | 1985 | 16664126 |
| lateral distribution of the cytochrome b(6)/f and coupling factor atp synthetase complexes of chloroplast thylakoid membranes. | we have visualized directly the distribution of the cytochrome b(6)/f and coupling factor atp synthetase complexes in thylakoid membranes of embedded, thin-sectioned, intact chloroplasts by using rabbit antibodies directed against each complex, followed by ferritin-conjugated goat anti- (rabbit immunoglobulin g) antibodies. the labeling patterns indicate that in spinach (spinacia oleracea) chloroplasts the cytochrome b(6)/f complex is distributed laterally throughout both stacked grana and unsta ... | 1985 | 16664197 |
| localization of cytochrome b-559 in the chloroplast thylakoid membranes in spinach. | cytochrome b-559 was purified from spinach leaves and antibodies were made against it in rabbit. using affinity-purified, monospecific antibodies, we have found that cytochrome b-559, which is closely associated with the primary photochemical activity of photosystem ii, is localized exclusively in the grana thylakoids. | 1986 | 16664569 |
| starch phosphorylase inhibitor from sweet potato. | a protein, starch phosphorylase inhibitor, was purified from the root of sweet potato (ipomoea batatas [l.] lam. cv tainon 65). it had a molecular weight of 250,000 and could be composed of five identical subunits. the isoelectric point of the inhibitor was 4.63. it was a noncompetitive inhibitor toward the sweet potato enzyme with a k(i) value of 1.3 x 10(-6) molar when glucose-1-p was the variable substrate. because cross-reacting materials of rabbit antiphosphorylase inhibitor of sweet potato ... | 1986 | 16664657 |
| polyphenoloxidase in higher plants: immunological detection and analysis of in vitro translation products. | antibodies to broad bean polyphenoloxidase (ppo) were used to detect and demonstrate that the ppos found in several different plants have many similarities in common. crude extracts from leaves of broad bean, bush bean, lettuce, mung bean, pea, soybean, spinach, tobacco, and tomato contained enzyme which cross-reacted with polyclonal anti-ppo in ouchterlony double diffusion analysis. the results suggested that plant polyphenoloxidase from a wide range of species may contain similar antigen deter ... | 1986 | 16664865 |
| microspectrofluorometric measurement of chloroplast dna in dividing and expanding leaf cells of spinacia oleracea. | absolute dna amounts of individual chloroplasts from mesophyll and epidermal cells of developing spinach leaves were measured by microspectrofluorometry using the dna-specific stain, 4,6-diamidino-2-phenyl indole, and the bacterium, pediococcus damnosus, as an internal standard. values obtained by this method showed that dna amounts of individual chloroplasts from mesophyll cells fell within a normal distribution curve, although mean dna amounts changed during leaf development and also differed ... | 1986 | 16664887 |
| activity of acyl carrier protein isoforms in reactions of plant fatty acid metabolism. | two forms of spinach acyl carrier protein (acp-i and acp-ii) have recently been characterized and found to be expressed in a tissue-specific manner (jb ohlrogge, tm kuo, 1985 j biol chem 260: 8032). to examine possible different functions for these acp isoforms, we have tested purified preparations of spinach leaf acp-i and acp-ii and escherichia coli acp in several in vitro reactions of fatty acid metabolism. total de novo fatty acid synthesis and malonyl-coa:acp transacylase do not appear to d ... | 1986 | 16665049 |
| esterolytic properties of leucine-proteinase, the leucine-specific serine proteinase from spinach (spinacia oleracea l.) leaves : a steady-state and pre-steady-state study. | steady-state and pre-steady-state kinetics for the hydrolysis of p-nitrophenyl esters of n-alpha-carbobenzoxy(-l-)amino acids catalyzed by leucine-proteinase were determined between ph 5 and 10 (i = 0.1 molar) at 23 +/- 0.5 degrees c. for the substrates considered: (a) the acylation step is rate-limiting in catalysis; (b) the ph profiles of k(cat) and k(cat)/k(m) reflect the ionization of two groups with pk(a) values ranging between 6.5 and 6.9, and 8.1 and 8.3 (probably, the histidine residue i ... | 1986 | 16665073 |
| purification and properties of nonproteolytic degraded adpglucose pyrophosphorylase from maize endosperm. | adpglucose pyrophosphorylase from developing endosperm tissue of starchy maize (zea mays) was purified 88-fold to a specific activity of 34 micromoles alpha-glucose-1-p produced per minute per milligram protein. rabbit antiserum to purified spinach leaf adpglucose pyrophosphorylase was able to inhibit pyrophosphorolysis activity of the purified enzyme by up to 90%. the final preparation yielded four major protein staining bands following sodium dodecyl sulfate polyacrylamide gel electrophoresis. ... | 1987 | 16665182 |
| biochemical and developmental characterization of multiple forms of catalase in tobacco leaves. | leaf extracts of both nicotiana tabacum and nicotiana sylvestris contain multiple forms of catalase (h(2)o(2):h(2)o(2) oxidoreductase, ec 1.11.1.6) which are separable at different ph values by chromatofocusing columns. marked changes in distribution of these catalases occur during seedling development and leaf maturation. the form of catalase eluting first (peak 1) was predominant during early seedling growth and present at all stages of development. two more acidic forms (peaks 2 and 3) appear ... | 1987 | 16665461 |
| purification and species distribution of rubisco activase. | ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) activase, a soluble chloroplast protein which promotes light-dependent rubisco activation, was partially purified from spinach chloroplasts by ion-exchange and gel-filtration fast protein liquid chromatography. the protein could also be isolated using rate zonal centrifugation in sucrose gradients followed by conventional ion-exchange on deae-cellulose. the active enzyme was composed of 44 and 41 kilodalton subunits. antibodies to the act ... | 1987 | 16665546 |
| dihydroxyacetone phosphate reductase in plants. | two forms of dihydroxyacetone phosphate reductase are present in spinach, soybean, pea, and mesophyll cells of corn leaves. an improved homogenizing medium was developed to measure this activity. the enzyme was detectable only after dialysis of the 35 to 70% saturated (nh(4))(2)so(4) fraction and the two forms were separated by chromatography on either deae cellulose or sephacryl s-200. about 80% of the reductase was one form in the chloroplast and the rest was a second form in the cytosol as de ... | 1988 | 16665901 |
| characterization of the rna required for biosynthesis of delta-aminolevulinic acid from glutamate : purification by anticodon-based affinity chromatography and determination that the uuc glutamate anticodon is a general requirement for function in ala biosynthesis. | the heme and chlorophyll precursor delta-aminolevulinic acid acid (ala) is formed in plants and algae from glutamate in a process that requires at least three enzyme components plus a low molecular weight rna which co-purifies with the trna fraction during deae-cellulose column chromatography. rna that is effective in the in vitro ala biosynthetic system was extracted from several plant and algal species that form ala via this route. in all cases, the effective rna contained the uuc glutamate an ... | 1988 | 16665935 |
| catalysis of ribulosebisphosphate carboxylase/oxygenase activation by the product of a rubisco activase cdna clone expressed in escherichia coli. | ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) activase activity was obtained from a partially purified extract of escherichia coli transformed with a 1.6-kilobase spinach (spinacia oleracea l.) cdna clone. this activity was atp-dependent. catalysis of rubisco activation by spinach and cloned rubisco activase was accompanied by the same extent of carboxyarabinitol bisphosphate-trapped (14)co(2) as occurred in spontaneous activation, indicating that rubisco carbamylation is one facet o ... | 1988 | 16666245 |
| isolation of dihydroxyacetone phosphate reductase from dunaliella chloroplasts and comparison with isozymes from spinach leaves. | a dihydroxyacetone phosphate (dhap) reductase has been isolated in 50% yield from dunaliella tertiolecta by rapid chromatography on diethylaminoethyl cellulose. the activity was located in the chloroplasts. the enzyme was cold labile, but if stored with 2 molar glycerol, most of the activity was restored at 30 degrees c after 20 minutes. the spinach (spinacia oleracea l.) reductase isoforms were not activated by heat treatment. whereas the spinach chloroplast dhap reductase isoform was stimulate ... | 1988 | 16666401 |
| evidence from solanum tuberosum in support of the dual-pathway hypothesis of aromatic biosynthesis. | key branchpoint enzymes of aromatic amino acid biosynthesis, 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (ds) and chorismate mutase (cm), have previously been shown to exist as separate compartmentalized isozymes in the chloroplasts and cytosol of tobacco, sorghum and spinach. although additional examples of plants containing these isozyme pairs are accumulating, some studies in the literature report the presence of only the single plastidic ds or cm enzyme. such apparent exceptions con ... | 1989 | 16666497 |
| an examination of the plastid dna of hypohaploid nicotiana plumbaginifolia plants. | dna was extracted from different morphological types of hypohaploid nicotiana plumbaginifolia plants. the cellular levels of chloroplast dna (expressed as percent of total dna) were found to be approximately two- to threefold higher in two albino hypohaploids than in a green hypohaploid. the level of chloroplast dna in the green hypohaploid was not significantly different from either in vitro or in vivo grown haploid n. plumbaginifolia plants. molecular hybridization with dna probes for the larg ... | 1989 | 16666781 |
| cloning of cdna sequences encoding the calcium-binding protein, calmodulin, from barley (hordeum vulgare l.). | full- and partial-length cdnas encoding calmodulin mrna have been cloned and sequenced from barley (hordeum vulgare l.). barley leaf mrna, size-fractionated in sucrose density gradients, was used to synthesize double-stranded cdna. the cdna was cloned in lambdagt10 and screened with a synthetic, 14-nucleotide oligonucleotide probe, which was designed using the predicted coding sequences of the carboxy termini of spinach and wheat calmodulin proteins. the primary structure of barley calmodulin, p ... | 1989 | 16666833 |
| species and environmental variations in the effect of inorganic phosphate on sucrose-phosphate synthase activity : reliability of assays based upon udp formation. | the effect of inorganic phosphate (pi) on sucrose-phosphate synthase (sps) activity was determined for the enzyme from five plant species (nicotiana tabacum l., spinacia oleracea l., triticum aestivum l., zea mays l., glycine max l.) using two assay methods. the assay method based on determination of uridine diphosphate glucose- (udpg) and fructose-6-phosphate-dependent sucrose formation was linear up to 15 minutes for all species tested. when assayed in this way, the effect of pi at levels of 5 ... | 1989 | 16667054 |
| analysis of chromophytic and rhodophytic ribulose-1,5-bisphosphate carboxylase indicates extensive structural and functional similarities among evolutionarily diverse algae. | ribulose-1,5-bisphosphate carboxylase (rubisco) from the algae olisthodiscus luteus (chromophyte) and griffithsia pacifica (rhodophyte) are remarkably similar to each other. however, both enzymes differ significantly in the structure and function when compared to rubisco from green algae and land plants. analysis of purified rubisco from o. luteus and g. pacifica indicates that the size of the holoenzyme and stoichiometry of the 55 and 15 kilodalton subunit polypeptides are approximately 550 kil ... | 1989 | 16667160 |
| structural similarities between spinach chloroplast and cytosolic class i fructose 1,6-bisphosphate aldolases : immunochemical and amino-terminal amino acid sequence analysis. | immunochemical studies using polyclonal antisera prepared individually against highly purified cytosolic and chloroplast spinach leaf (spinacia oleracea) fructose bisphosphate aldolases showed significant cross reaction between both forms of spinach aldolase and their heterologous antisera. the individual cross reactions were estimated to be approximately 50% in both cases under conditions of antibody saturation using a highly sensitive enzyme-linked immunosorbent assay. in contrast, the class i ... | 1989 | 16667191 |
| evidence for a universal pathway of abscisic acid biosynthesis in higher plants from o incorporation patterns. | previous labeling studies of abscisic acid (aba) with (18)o(2) have been mainly conducted with water-stressed leaves. in this study, (18)o incorporation into aba of stressed leaves of various species was compared with (18)o labeling of aba of turgid leaves and of fruit tissue in different stages of ripening. in stressed leaves of all six species investigated, avocado (persea americana), barley (hordeum vulgare), bean (phaseolus vulgaris), cocklebur (xanthium strumarium), spinach (spinacia olerac ... | 1989 | 16667222 |
| identification of the large subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase as a substrate for transglutaminase in medicago sativa l. (alfalfa). | extracts prepared from floral meristematic tissue of alfalfa (medicago sativa l.) were investigated for expression of the enzyme transglutaminase in order to identify the major protein substrate for transglutaminase-directed modifications among plant proteins. the large polymorphic subunits of ribulose 1,5-bisphosphate carboxylase/oxygenase in alfalfa, with molecular weights of 52,700 and 57,600, are major substrates for transglutaminase in these extracts. this was established by: (a) covalent c ... | 1990 | 16667270 |
| purification by immunoadsorption and immunochemical properties of nadp-dependent malic enzymes from leaves of c(3), c(4), and crassulacean acid metabolism plants. | nadp:malic enzyme from corn (zea mays l.) leaves was purified by conventional techniques to apparent homogeneity as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. antibodies raised against this protein in rabbits were purified, coupled covalently to protein a-sepharose cl-4b, and used as an immunoaffinity resin to purify the nadp:malic enzymes of the c(3) plants spinach (spinacia oleracea l.) and wheat (triticum aestivum l.), of the crassulacean acid metabolism (cam) plant ... | 1990 | 16667339 |
| purification and characterization of a ferredoxin-nadp oxidoreductase-like enzyme from radish root tissues. | an enzyme able to reduce cytochrome c via ferredoxin in the presence of nadph, was isolated, purified from radish (raphanus sativus var acanthiformis cultivar miyashige) roots and characterized. the enzyme was purified by deae-cellulose, blue-cellulofine, ferredoxin-sepharose 4b, and sephadex g-100 column chromatography. molecular mass of the enzyme was estimated to be 33,000 and 35,000 daltons by sephadex g-100 gel filtration and sds-page, respectively. its absorption spectrum suggested that th ... | 1990 | 16667598 |
| isolation and characterization of a cdna coding for pea chloroplastic carbonic anhydrase. | using a polyclonal antibody generated against the purified pea (pisum sativum) carbonic anhydrase (ca) monomeric species, we have isolated and characterized a cdna coding for this enzyme. protein sequence analysis was used to confirm the identity of the clone. the presence of a large transit peptide suggests that ca is transported into the chloroplast and then processed to the mature size of approximately 26 kilodaltons. northern hybridization, using the ca cdna as a probe of total leaf rna, rev ... | 1991 | 16667962 |
| dissipation of the proton electrochemical potential in intact and lysed chloroplasts : i. the electrical potential. | effective ionophore:chlorophyll ratios were determined for various ionophores that decrease the electrical potential across thylakoid membranes in intact and hypo-osmotically lysed chloroplasts isolated from spinach (spinacia oleracea). the efficacy of gramicidin d, valinomycin, carbonylcyanide m-chlorophenylhydrazone, and dicyclohexano-18-crown-6 in collapsing the electrical potential was determined spectrophotometrically by the decay half-time of the absorbance change at 518 nanometers induced ... | 1991 | 16668015 |
| regulatory and structural properties of the cyanobacterial adpglucose pyrophosphorylases. | adpglucose pyrophosphorylase (ec 2.7.7.27) has been purified from two cyanobacteria: the filamentous, heterocystic, anabaena pcc 7120 and the unicellular synechocystis pcc 6803. the purification procedure gave highly purified enzymes from both cynobacteria with specific activities of 134 (synechocystis) and 111 (anabaena) units per milligram protein. the purified enzymes migrated as a single protein band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis with molecular mass correspondi ... | 1991 | 16668507 |
| partial purification and characterization of ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit epsilonn-methyltransferase. | the large subunit (ls) of tobacco (nicotiana rustica) ribulose-1,5-bisphosphate carboxylase/oxygenase (ribulose-p(2) carboxylase) contains a trimethyllysyl residue at position 14, whereas this position is unmodified in spinach ribulose-p(2) carboxylase. a protein fraction was isolated from tobacco chloroplasts by rate-zonal centrifugation and anion-exchange fast protein liquid chromatography that catalyzed transfer of methyl groups from s-adenosyl-[methyl-(3)h]-l-methionine to spinach ribulose-p ... | 1991 | 16668531 |
| identification of gibberellins in spinach and effects of light and darkness on their levels. | the endogenous gibberellin (ga) content of spinach (spinacia oleracea) was reinvestigated by combined gas chromatography-mass spectrometry analysis. the 13-hydroxy gas: ga(53), ga(44), ga(19), ga(17), ga(20), ga(5), ga(1), ga(29), and ga(8); the non-3, 13-hydroxy gas: ga(12), ga(15), ga(9), and ga(51); and the 3beta-hydroxy gas: ga(4), ga(7), and ga(34), were identified in spinach extracts by comparing full-scan mass spectra and kovats retention indices with those of reference gas. in addition, ... | 1991 | 16668579 |
| stromal low temperature compartment derived from the inner membrane of the chloroplast envelope. | leaf discs of four dicotyledonous species, when incubated at temperatures of 4 to 18 degrees c (optimum at 12 degrees c) for 30 or 60 minutes, responded by accumulations of membranes in the chloroplast stroma in the space between the inner membrane of the envelope and the thylakoids. the accumulated membranes, here referred to as the low temperature compartment, were frequently continuous with the envelope membrane and exhibited kinetics of formation consistent with a derivation from the envelop ... | 1991 | 16668584 |
| purification and molecular and immunological characterization of a unique phosphoribulokinase from the green alga selenastrum minutum. | a unique phosphoribulokinase (adp:d-ribulose 5-phosphate 1-phosphotransferase, ec 2.7.1.19) has been purified to homogeneity from the green alga selenastrum minutum. the enzyme has a native molecular mass of about 83 kilodaltons and a native isoelectric point of 5.1. the enzyme consists of two different-sized subunits of 41 and 40 kilodaltons, implying that it is a heterodimer. this is the first report of a eukaryotic heterodimeric phosphoribulokinase. the in vivo existence of two nonidentical s ... | 1992 | 16668652 |
| simple determination of the co(2)/o(2) specificity of ribulose-1,5-bisphosphate carboxylase/oxygenase by the specific radioactivity of [c]glycerate 3-phosphate. | a new method is presented for measurement of the co(2)/o(2) specificity factor of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco). the [(14)c]3-phosphoglycerate (pga) from the rubisco carboxylase reaction and its dilution by the rubisco oxygenase reaction was monitored by directly measuring the specific radioactivity of pga. (14)co(2) fixation with rubisco occurred under two reaction conditions: carboxylase with oxygenase with 40 micromolar co(2) in o(2)-saturated water and carboxylase ... | 1992 | 16668709 |
| characterization of the activation of membrane-bound and soluble cf(1) by thioredoxin. | the activation of spinach (spinacia oleracea) chloroplast coupling factor 1 (cf(1)) by thioredoxin (thr) was characterized using membrane-bound and soluble cf(1). light generates an electrochemical proton gradient across the thylakoid membrane, which increases the accessibility of the disulfide bond on the gamma-subunit of cf(1) to reduced thr. the proton gradient substantially accelerates the activation of cf(1) compared with thylakoids incubated in the dark with similar concentrations of dithi ... | 1992 | 16668843 |
| assembly of two subunits of the cyanobacterial photosystem i on the n-side of thylakoid membranes. | photosystem i contains several peripheral membrane proteins that are located on either positive (luminal) or negative (stromal or cytoplasmic) sides of thylakoid membranes of chloroplasts or cyanobacteria. incorporation of two peripheral subunits into photosystem i of the cyanobacterium synechocystis species pcc 6803 was studied using a reconstitution system in which radiolabeled subunits ii (psad) and iv (psae) were synthesized in vitro and incubated with the isolated thylakoid membranes. after ... | 1992 | 16668856 |
| regulation of photosynthesis by end-product accumulation in leaves of plants storing starch, sucrose, and hexose sugars. | in the present study, leaves of different plant species were girdled by the hot wax collar method to prevent export of assimilates. photosynthetic activity of girdled and control leaves was evaluated 3 to 7 days later by two methods: (a) carbon exchange rate (cer) of attached leaves was determined under ambient co(2) concentrations using a closed gas system, and (b) maximum photosynthetic capacity (a(max)) was determined under 3% co(2) with a leaf disc o(2) electrode. starch, hexoses, and sucros ... | 1992 | 16669056 |
| description of a novel panallergen of cross-reactivity between moulds and foods. | the present investigation is undertaken to demonstrate a novel cross-reactivity between aeroallergens (moulds fungi imperfecti) and allergens from foods (spinach and mushroom agaricus bisporus). we have performed a dual study in vivo and in vitro, in a population of atopic patients. data from in vivo tests performed with spinach and mushroom have been statistically analysed. to the in vitro assays, mushroom and spinach extracts have been obtained, and sera from moulds allergic patients analysed ... | 2006 | 16698676 |
| identification of critical arginine residues in the functioning of rubisco activase. | rubisco activase is a member of the aaa(+) family in which arginines located in the box vii and sensor 2 domains are a recurrent feature and typically contribute to atp-binding/hydrolysis or an inter-subunit interface. replacement of r241 or r244 in box vii or r294 or r296 in sensor 2 with alanine in tobacco activase did not greatly alter the binding of atp or adp. however, atp hydrolysis was minimal (r241a and r244a) or greatly diminished (r296a) and none of these mutants were able to activate ... | 2006 | 16712773 |
| refinement of the structural model for the photosystem ii supercomplex of higher plants. | recent x-ray structures determined for the photosystem ii (psii) core complex isolated from cyanobacteria have provided important information for understanding the functionality of this photosynthetic enzyme including its water splitting activity. as yet, no high-resolution structure is available for psii of plants or eukaryotes in general. however, crystal structures have been determined for some components of plant psii which together with the cyanobacterial structure can be used to interpret ... | 2006 | 16729961 |
| quality control of photosystem ii. cleavage of reaction center d1 protein in spinach thylakoids by ftsh protease under moderate heat stress. | when spinach thylakoids were subjected to moderate heat stress (40 degrees c for 30 min), oxygen evolution was inhibited, and cleavage of the reaction center-binding protein d1 of photosystem ii took place, producing 23-kda n-terminal fragments. the d1 cleavage was greatly facilitated by the addition of 0.15 mm zncl2 and 1 mm atp and was completely inhibited by 1 mm edta, indicating the participation of an atp-dependent metalloprotease(s) in the d1 cleavage. herbicides 3-(3,4-dichlorophenyl)-1,1 ... | 2006 | 16735503 |
| accumulation of glycinebetaine in rice plants that overexpress choline monooxygenase from spinach and evaluation of their tolerance to abiotic stress. | glycinebetaine (gb), a quaternary ammonium compound, is a very effective compatible solute. in higher plants, gb is synthesized from choline (cho) via betaine aldehyde (ba). the first and second steps in the biosynthesis of gb are catalysed by choline monooxygenase (cmo) and by betaine aldehyde dehydrogenase (badh), respectively. rice (oryza sativa), which has two genes for badh, does not accumulate gb because it lacks a functional gene for cmo. rice plants accumulate gb in the presence of exoge ... | 2006 | 16790464 |
| pythiogeton zizaniae, a new species causing basal stalk rot of water bamboo in taiwan. | a new species, pythiogeton zizaniae, was isolated from diseased water bamboo (zizania latifolia) in central taiwan. the organism formed a colony with scanty mycelia and mycelial aggregates on rye-water bamboo medium. special treatments were required for production of sporangia which were terminal, noncaducous and mostly ovoid. chlamydospores were absent. the fungus was homothallic. oogonia produced on v-8 water bamboo medium in water were mostly globose to subglobose and each was attached with a ... | 2006 | 16800309 |
| an inserted loop region of stromal ascorbate peroxidase is involved in its hydrogen peroxide-mediated inactivation. | ascorbate peroxidase isoforms localized in the stroma and thylakoid of higher plant chloroplasts are rapidly inactivated by hydrogen peroxide if the second substrate, ascorbate, is depleted. however, cytosolic and microbody-localized isoforms from higher plants as well as ascorbate peroxidase b, an ascorbate peroxidase of a red alga galdieria partita, are relatively tolerant. we constructed various chimeric ascorbate peroxidases in which regions of ascorbate peroxidase b, from sites internal to ... | 2006 | 16817898 |
| lipids in oxygen-evolving photosystem ii complexes of cyanobacteria and higher plants. | lipids in dimeric photosystem ii complexes prepared from two species of cyanobacteria, thermosynechococcus vulcanus and synechocystis sp. pcc6803, and two higher plants, spinach and rice, were analyzed to determine how many lipid molecules and what class of lipids are present in the photosystem ii complexes. it was estimated that 27, 20, 8, and 7 lipid molecules per monomer are bound to the dimeric photosystem ii complexes of t. vulcanus, synechocystis, spinach, and rice, respectively. in each o ... | 2006 | 16822813 |
| the rate of intestinal absorption of natural food folates is not related to the extent of folate conjugation. | evidence is conflicting as to whether the bioavailability of food folates is influenced by the extent of their conjugation. | 2006 | 16825692 |
| characterization of the water oxidizing complex of photosystem ii of the chl d-containing cyanobacterium acaryochloris marina via its reactivity towards endogenous electron donors and acceptors. | acaroychloris (a.) marina is a unique oxygen evolving organism that contains a large amount of chlorophyll d (chl d) and only very few chl a molecules. this feature raises questions on the nature of the photoactive pigment, which supports light-induced oxidative water splitting in photosystem ii (ps ii). in this study, flash-induced oxygen evolution patterns (fiops) were measured to address the question whether the s(i) state transition probabilities and/or the redox-potentials of the water oxid ... | 2006 | 16855726 |
| a simple in vitro rna editing assay for chloroplast transcripts using fluorescent dideoxynucleotides: distinct types of sequence elements required for editing of ndh transcripts. | rna editing is found in various transcripts from land plant chloroplasts. in tobacco chloroplasts, c-to-u conversion occurs at 36 specific sites including two sites identified in this work. our rna editing assay system using chloroplast extracts facilitated biochemical analyses of editing reactions but required mrnas labeled with (32)p at specific sites. here, we have improved the in vitro system using fluorescence-labeled chain terminators, ddgtp and ddatp, and have measured the editing activit ... | 2006 | 16856984 |
| formation of methyl mercury in an aquatic macrophyte. | in the nature, inorganic forms of mercury (hg) may be transformed to the organic, very toxic, methyl-hg. occasionally methyl-hg has been detected in plants, also so in the aquatic macrophyte water spinach (ipomoea aquatica), which is a popular vegetable in tropical regions. the objectives of this study were to investigate if methyl-hg is formed and/or degraded in water spinach. water spinach plants were exposed to inorganic hg via spiked soil or spiked nutrient solution. tests were performed in ... | 2006 | 16872659 |
| heavy metal load of soil, water and vegetables in peri-urban delhi. | peri-urban lands are often used for production of vegetables for better market accessibility and higher prices. but most of these lands are contaminated with heavy metals through industrial effluents, sewage and sludge, and vehicular emission. vegetables grown in such lands, therefore, are likely to be contaminated with heavy metals and unsafe for consumption. samples of vegetables i.e., spinach (spinacia oleracea l.) and okra (abelmoschus esculentus l.); soil and irrigation water were collected ... | 2006 | 16897527 |
| reduction enhances yields of nitric oxide trapping by iron-diethyldithiocarbamate complex in biological systems. | the mechanism of no trapping by iron-diethylthiocarbamate complexes was investigated in cultured cells and animal and plant tissues. contrary to common belief, the no radicals are trapped by iron-diethylthiocarbamates not only in ferrous but in ferric state also in the biosystems. when detc was excess over endogenous iron ligands like citrate, ferric detc complexes were directly observed with epr spectroscopy at g=4.3. this was the case when isolated spinach leaves, endothelial cultured cells we ... | 2007 | 16938475 |
| effect of gamma-irradiation on pathogens inoculated into ready-to-use vegetables. | three ready-to-use vegetables, cucumber, blanched and seasoned spinach, and seasoned burdock were selected and the effects of an irradiation treatment for eliminating pathogens were investigated. the pathogens tested were salmonella typhimurium, escherichia coli, staphylococcus aureus, and listeria ivanovii. inoculated viable cells of s. typhimurium and l. ivanovii into cucumber and blanched and seasoned spinach were reduced about 4 decimal points by 2 kgy of irradiation and that of s. aureus in ... | 2006 | 16943064 |
| response of spinach and komatsuna to biogas effluent made from source-separated kitchen garbage. | recycling of kitchen garbage is an urgent task for reducing public spending and environmental burdens by incineration and/or landfill. there is an interesting regional effort in ogawa, saitama prefecture, japan, in which source-separated kitchen garbage is anaerobically fermented with a biogas plant and the resultant effluent is used as a quick-release organic fertilizer by surrounding farmers. however, scientific assessments of fertilizer values and risks in the use of the effluent were lacking ... | 2006 | 16973635 |
| fda warns us consumers not to eat spinach after e coli outbreak. | | 2006 | 17008660 |
| importance of culture confirmation of shiga toxin-producing escherichia coli infection as illustrated by outbreaks of gastroenteritis--new york and north carolina, 2005. | escherichia coli o157:h7 and other strains of e. coli that produce shiga toxin are collectively known as shiga toxin-producing e. coli (stec). the current outbreak of stec o157 infections associated with eating fresh spinach illustrates the importance of obtaining isolates to identify the source of the infections. laboratory methods that do not require bacterial culture of stool specimens to identify stec are being used increasingly by clinical diagnostic laboratories, sometimes without subseque ... | 2006 | 17008867 |
| ongoing multistate outbreak of escherichia coli serotype o157:h7 infections associated with consumption of fresh spinach--united states, september 2006. | on september 13, 2006, cdc officials were alerted by epidemiologists in wisconsin and oregon that fresh spinach was the suspected source of small clusters of escherichia coli serotype o157:h7 infections in those states. on the same day, new mexico epidemiologists contacted wisconsin and oregon epidemiologists about a cluster of e. coli o157:h7 infections in new mexico associated with fresh spinach consumption. wisconsin public health officials had first reported a cluster of e. coli o157:h7 infe ... | 2006 | 17008868 |
| simultaneous preconcentration and determination of copper, nickel, cobalt and lead ions content by flame atomic absorption spectrometry. | a sensitive and simple method for the simultaneous preconcentration of nutritionally important minerals in real samples has been reported. the method is based on the formation of metal complexes by 4,6-dihydroxy-2-mercaptopyrimidine (dhmp) loaded on activated carbon. the metals content on the complexes are then eluted using 5 ml 2m hno(3) in acetone, which are detected by aas at resonance line. in this procedure, minerals such as cu, ni, pb and co could be analyzed in one run by caring out the s ... | 2007 | 17011124 |
| phenolic constituents of celosia cristata l. susceptible to spinach root rot pathogen aphanomyces cochlioides. | cochliophilin a (5-hydroxy-6,7-methylenedioxyflavone, 1), known as a host-specific attractant towards the zoospores of aphanomyces cochlioides, a cause of root rot and damping-off diseases of chenopodiaceae, was found in the amaranthaceae plant, celosia cristata, that is susceptible to the pathogen. the content of 1 in celosia seedlings was quantified as 1.4 microg/g fresh weight. a new isoflavone, cristatein (5-hydroxy-6-hydroxymethyl-7,2'-dimethoxyisoflavone, 2), and five known flavonoids were ... | 2006 | 17031042 |
| thioredoxin-dependent regulation of photosynthetic glyceraldehyde-3-phosphate dehydrogenase: autonomous vs. cp12-dependent mechanisms. | regulation of the calvin-benson cycle under varying light/dark conditions is a common property of oxygenic photosynthetic organisms and photosynthetic glyceraldehyde-3-phosphate dehydrogenase (gapdh) is one of the targets of this complex regulatory system. in cyanobacteria and most algae, photosynthetic gapdh is a homotetramer of gapa subunits which do not contain regulatory domains. in these organisms, dark-inhibition of the calvin-benson cycle involves the formation of a kinetically inhibited ... | 2006 | 17031544 |
| spinach cultigen variation for tissue carotenoid concentrations influences human serum carotenoid levels and macular pigment optical density following a 12-week dietary intervention. | increasing intakes of carotenoid-rich plant foods can increase serum carotenoid concentrations and macular pigment optical density (mpod) in most, but not all, individuals. research objectives for this study were to (1) characterize tissue lutein (l) and beta-carotene (bc) concentrations in carotenoid-rich spinach (spinacia oleracea l.) cultigens and (2) determine serum carotenoid and mpod responses in human subjects consuming spinach cultigens differing in tissue l and bc concentrations. thirte ... | 2006 | 17032001 |
| determining rubisco activation kinetics and other rate and equilibrium constants by simultaneous multiple non-linear regression of a kinetic model. | the forward and reverse rate constants involved in carbamylation, activation, carboxylation, and inhibition of d-ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) have been estimated by a new technique of simultaneous non-linear regression of a differential equation kinetic model to multiple experimental data. parameters predicted by the model fitted to data from purified spinach enzyme in vitro included binding affinity constants for non-substrate co2 and mg2+ of 200+/-80 microm and 700 ... | 2006 | 17046981 |
| understanding electron transport systems of streptomyces cytochrome p450. | streptomyces spp. are known to produce various types of biologically active compounds including antibiotics, antiparasitic agents, herbicides and immunosuppressants. p450 (cytochrome p450) enzymes may have key roles in these biosynthetic and biotransformation reactions. recent genomic analysis of streptomyces coelicolor a3(2) indicates that s. coelicolor may have six ferredoxins (fdxs), four putative fdx reductases (fdrs) and 18 p450 genes. however, there are few clues to explain the mechanisms ... | 2006 | 17073781 |
| using ecosan sludge for crop production. | this paper presents the microbial risks associated with the reuse of ecosan sludge in agriculture. sludge from kwazulu natal province in south africa with a helminth ova content of 30 ho/g ts, faecal coliforms of 10(6) cfu/g ts, faecal streptococci of 10(6) cfu/g ts and salmonella spp. of 10(5) cfu/g ts was used for this purpose. applying different rates of sludge to spinach and carrots resulted in an increase in bacterial and helminth ova counts in crops as the quantity of sludge increased. the ... | 2006 | 17087383 |
| structural perturbation of the carboxylate ligands to the manganese cluster upon ca2+/sr2+ exchange in the s-state cycle of photosynthetic oxygen evolution as studied by flash-induced ftir difference spectroscopy. | a ca(2+) ion is an indispensable element in the oxygen-evolving mn cluster in photosystem ii (psii). to investigate the structural relevance of ca(2+) to the mn cluster, the effects of sr(2+) substitution for ca(2+) on the structures and reactions of ligands to the mn cluster during the s-state cycle were investigated using flash-induced fourier transform infrared (ftir) difference spectroscopy. ftir difference spectra representing the four s-state transitions, s(1) --> s(2), s(2) --> s(3), s(3) ... | 2006 | 17087499 |
| don't eat the spinach--controlling foodborne infectious disease. | | 2006 | 17093245 |
| e. coli o157:h7 outbreak in the united states associated with bagged fresh spinach. | | 2006 | 17115512 |
| structure-activity relationship of a glycolipid, sulfoquinovosyl diacylglycerol, with the dna binding activity of p53. | the in vitro relationship between the human p53 dna binding domain (p53 dbd) and glycolipids was investigated. we isolated the glycolipid fraction from spinach (spinacia oleracea l.) and found that the fraction inhibited the double-stranded dna (dsdna) binding activity of p53 dbd. since the fraction contained mainly three glycolipids, monogalactosyl diacylglycerol (mgdg), digalactosyl diacylglycerol (dgdg) and sulfoquinovosyl diacylglycerol (sqdg), and each glycolipid was purified using silica g ... | 2007 | 17143546 |
| fungal heme oxygenases: functional expression and characterization of hmx1 from saccharomyces cerevisiae and cahmx1 from candida albicans. | heme oxygenases convert heme to free iron, co, and biliverdin. saccharomyces cerevisiae and candida albicans express putative heme oxygenases that are required for the acquisition of iron from heme, a critical process for fungal survival and virulence. the putative heme oxygenases hmx1 and cahmx1 from s. cerevisiae and c. albicans, respectively, minus the sequences coding for c-terminal membrane-binding domains, have been expressed in escherichia coli. the c-terminal his-tagged, truncated enzyme ... | 2006 | 17144670 |
| transcriptional control of anthocyanin biosynthetic genes in the caryophyllales. | anthocyanins and betacyanins, two types of red pigment, have never been found to occur together in plants. although anthocyanins are widely distributed in higher plants, betacyanins have replaced anthocyanins in the caryophyllales. the accumulation of flavonols in the caryophyllales suggests that the step(s) of anthocyanin biosynthesis from dihydroflavonols to anthocyanins could be blocked in the caryophyllales. dihydroflavonol 4-reductase (dfr) and anthocyanidin synthase (ans) cdnas were isolat ... | 2007 | 17185736 |
| the s1yz* metalloradical epr signal of photosystem ii contains two distinct components that advance respectively to the multiline and g = 4.1 conformations of s2. | the s2 state of the oxygen-evolving complex (oec) of photosystem ii is heterogeneous, exhibiting two main epr spectral forms, the multiline and the g = 4.1 signal. it is not clearly established whether this heterogeneity develops during the s1 to s2 transition or is already present in the precursor states. we have compared the spectra of the s1yz* intermediate, obtained by visible light excitation (induction of charge separation) of the s1 state at liquid he temperatures, (s1yz*)vis, or by near- ... | 2007 | 17198391 |
| regulation of gibberellin 20-oxidase1 expression in spinach by photoperiod. | the multifunctional gibberellin (ga) 20-oxidase [ga(53), 2-oxoglutarate:oxygen oxidoreductase (20-oxidizing), ec 1.14.11] has been extensively investigated in various species at the genetic and molecular levels, but not at the protein level. here, we report on expression of ga20ox1 protein in spinach (spinacia oleracea l.) in response to photoperiod. polyclonal antibodies were raised against recombinant soga20ox1 in a chicken. these antibodies immuno-inhibited the enzymatic activity of the recom ... | 2007 | 17216482 |
| purification, microsequencing and cloning of spinach atp-dependent phosphofructokinase link sequence and function for the plant enzyme. | despite its importance in plant metabolism, no sequences of higher plant atp-dependent phosphofructokinase (ec 2.7.1.11) are annotated in the databases. we have purified the enzyme from spinach leaves 309-fold to electrophoretic homogeneity. the purified enzyme was a homotetramer of approximately 52 kda subunits with a specific activity of 600 mu x mg(-1) and a km value for atp of 81 microm. the purified enzyme was not activated by phosphate, but slightly inhibited instead, suggesting that it wa ... | 2007 | 17229148 |
| corrections to the report of san mateo county enterohemorrhagic escherichia coli o157:h7 outbreak associated with raw spinach. | | 2007 | 17233709 |
| identification, expression, and functional analyses of a thylakoid atp/adp carrier from arabidopsis. | in plants the chloroplast thylakoid membrane is the site of light-dependent photosynthetic reactions coupled to atp synthesis. the ability of the plant cell to build and alter this membrane system is essential for efficient photosynthesis. a nucleotide translocator homologous to the bovine mitochondrial adp/atp carrier (aac) was previously found in spinach thylakoids. here we have identified and characterized a thylakoid atp/adp carrier (taac) from arabidopsis.(i) sequence homology with the bovi ... | 2007 | 17261580 |
| biophysics and bioinformatics reveal structural differences of the two peripheral stalk subunits in chloroplast atp synthase. | atp synthases convert an electrochemical proton gradient into rotational movement to produce the ubiquitous energy currency adenosine triphosphate. tension generated by the rotational torque is compensated by the stator. for this task, a peripheral stalk flexibly fixes the hydrophilic catalytic part f1 to the membrane integral proton conducting part f(o) of the atp synthase. while in eubacteria a homodimer of b subunits forms the peripheral stalk, plant chloroplasts and cyanobacteria possess a h ... | 2007 | 17283010 |
| leafy, green, healthful--but contaminated. the e. coli outbreak from bagged spinach is a reminder that fruit and vegetables can harbor harmful bacteria. | | 2006 | 17297727 |
| a database of pcr primers for the chloroplast genomes of higher plants. | chloroplast genomes evolve slowly and many primers for pcr amplification and analysis of chloroplast sequences can be used across a wide array of genera. in some cases 'universal' primers have been designed for the purpose of working across species boundaries. however, the essential information on these primer sequences is scattered throughout the literature. | 2007 | 17326828 |
| ct imaging of acute e. coli-related colitis. | patients with abdominal pain and bloody diarrhea often present in the acute setting to the emergency department for evaluation. after the appropriate clinical assessment, cross-sectional imaging is often utilized to evaluate for the severity of the disease. although a wide spectrum of findings may be seen, diffuse colonic mural thickening, consistent with pancolitis, is most common. we report an escherichia coli 0157:h7-related pancolitis in a patient with spinach intake linked to the recent out ... | 2007 | 17333084 |
| the fda: fresh leafy greens grown in the united states are safe. | every year, there are many thousands of pounds of fresh leafy greens, such as lettuce and spinach, grown in the united states and eaten by the public with no consequent illness. outbreaks, however, such as the recent escherichia coli (e. coli) o157:h7 outbreak linked to raw spinach, do occur, and there is a need to do everything possible to minimize the likelihood of further outbreaks and to prevent serious illness. the food and drug administration has taken a number of actions in recent years, ... | 2006 | 17333559 |
| dietary lutein modulates inducible nitric oxide synthase (inos) gene and protein expression in mouse macrophage cells (raw 264.7). | lutein is an oxycarotenoid primarily found in dark-green leafy vegetables such as spinach and kale. other dietary sources which contain moderate amounts of lutein include corn, egg yolks, and fruits like oranges and kiwi. although a number of in vivo studies have demonstrated the anti-inflammatory effect of lutein, its in vitro anti-inflammatory molecular mechanism of action is unknown. in this study, we have investigated the in vitro anti-inflammatory effect of lutein using lps-stimulated mouse ... | 2007 | 17340577 |
| mechanistic diversity in the rubisco superfamily: the "enolase" in the methionine salvage pathway in geobacillus kaustophilus. | d-ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco), the most abundant enzyme, is the paradigm member of the recently recognized mechanistically diverse rubisco superfamily. the rubisco reaction is initiated by abstraction of the proton from c3 of the d-ribulose 1,5-bisphosphate substrate by a carbamate oxygen of carboxylated lys 201 (spinach enzyme). heterofunctional homologues of rubisco found in species of bacilli catalyze the tautomerization ("enolization") of 2,3-diketo-5-methylthio ... | 2007 | 17352497 |
| perturbation of the structure of p680 and the charge distribution on its radical cation in isolated reaction center complexes of photosystem ii as revealed by fourier transform infrared spectroscopy. | the structure and the electronic properties of p680 and its radical cation in photosystem ii (psii) were studied by means of fourier transform infrared spectroscopy (ftir). light-induced p680+/p680 ftir difference spectra in the mid- and near-ir regions were measured using psii membranes from spinach, core complexes from thermosynechococcus elongatus, and reaction center (rc) complexes (d1-d2-cytb559) from spinach. the spectral features of the former two preparations were very similar, indicatin ... | 2007 | 17371054 |
| delayed fluorescence observed in the nanosecond time region at 77 k originates directly from the photosystem ii reaction center. | the excited-state dynamics of delayed fluorescence in photosystem (ps) ii at 77 k were studied by time-resolved fluorescence spectroscopy and decay analysis on three samples with different antenna sizes: ps ii particles and the ps ii reaction center from spinach, and the ps ii core complexes from synechocystis sp. pcc 6803. delayed fluorescence in the nanosecond time region originated from the 683-nm component in all three samples, even though a slight variation in lifetimes was detected from 15 ... | 2007 | 17382895 |
| application of pressurized fluid extraction to determine cadmium and zinc in plants. | a procedure for the determination of cd and zn in plants is proposed. the metals are extracted by pressurized fluid extraction (pfe). operational conditions are: pressure 1500 psi, temperature 75 degrees c, static time 5 min, flush volume 35%, purge time 60s, cycles 1 and 1,2-diaminocyclohexane-n,n,n',n'-tetraacetic acid (cdta) 0.01m at ph 4.5 as extracting solution. determination of zn is carried out by flame atomic absorption spectroscopy and depending on the concentration level, cd content is ... | 2007 | 17386428 |