| reversible, non-denaturing metal substitution in bovine adrenodoxin and spinach ferredoxin and the different reactivities of [2fe-2s]-cluster-containing proteins. | the non-denaturing substitution of cluster iron by other metals was studied in spinach ferredoxin and in bovine adrenodoxin. only some of several metal species tested (cd2+, zn2+, vo2+, mn2+, co2+, ni2+) caused bleaching of the residual visible absorbance and of the epr signals of the reduced ferredoxins. no formation of mixed-metal cluster was observed. the most reactive metal species were cd2+ and zn2+ and cd2+ was found to react also with oxidized adrenodoxin. metal-treated proteins were reso ... | 1996 | 8774731 |
| the function and properties of the iron-sulfur center in spinach ferredoxin: thioredoxin reductase: a new biological role for iron-sulfur clusters. | thioredoxin reduction in chloroplasts is catalyzed by a unique class of disulfide reductases which use a [2fe-2s]2+/+ ferredoxin as the electron donor and contain an fe-s cluster as the sole prosthetic group in addition to the active-site disulfide. the nature, properties, and function of the fe-s cluster in spinach ferredoxin:thioredoxin reductase (ftr) have been investigated by the combination of uv/visible absorption, variable-temperature magnetic circular dichroism (mcd), epr, and resonance ... | 1996 | 8784198 |
| identification of residues of spinach thioredoxin f that influence interactions with target enzymes. | the necessity for two types of thioredoxins (trx f and m) within chloroplasts of higher plants that mediate the same redox chemistry with various target enzymes is not well understood. to approach this complex issue, we have applied site-directed mutagenesis to the identification of residues of trx f that affect its binding to and selectivity for target enzymes. based upon amino acid sequence alignments and the three-dimensional structure of escherichia coli thioredoxin, putative key residues of ... | 1996 | 8798742 |
| phosphorylated nitrate reductase from spinach leaves is inhibited by 14-3-3 proteins and activated by fusicoccin. | nitrate reductase (nr) in leaves is rapidly inactivated in the dark by a two-step mechanism in which phosphorylation of nr on the serine at position 543 (ser543) promotes binding to nitrate reductase inhibitor protein (nip). the eukaryotic 14-3-3 proteins bind to many mammalian signalling components (raf-1, bcr, phosphoinositide 3-kinase, protein kinase c, polyomavirus middle-t antigen and cdc25), and are implicated in the timing of mitosis, dna-damage checkpoint control, exocytosis, and activat ... | 1996 | 8805370 |
| the effect of sulfite on the atp hydrolysis and synthesis activities in chloroplasts and cyanobacterial membrane vesicles can be explained by competition with phosphate. | the effect of sulfite on atp synthesis and hydrolysis activities is investigated in spinach chloroplasts and in membrane vesicles from the cyanobacterium synechococcus 6716. sulfite inhibits phenazine methosulfate-mediated cyclic photophosphorylation both in thiol-modulated chloroplasts and in cyanobacterial membranes with hso3- (bisulfite) as the active ionic species. the observed inhibition is not due to inhibition of electron transfer or to uncoupling by sulfite. atp synthesis in cyanobacteri ... | 1996 | 8806722 |
| effect of food composition on vitamin k absorption in human volunteers. | the human vitamin k requirement is not known precisely, but the minimal requirement is often assumed to be between 0.5 and 1 x 10(-6) g/kg body weight. in the present study we addressed the question to what extent circulating vitamin k concentrations are influenced by the form in which the vitamer is consumed. the experimental group consisted of five healthy volunteers who received phylloquinone after an overnight fast. on the first day of three successive weeks the participants consumed 1 mg (2 ... | 1996 | 8813897 |
| c-terminal truncation of spinach chloroplast nad(p)-dependent glyceraldehyde-3-phosphate dehydrogenase prevents inactivation and reaggregation. | chloroplast nad(p)-dependent glyceraldehyde-3-phosphate dehydrogenase (nad(p)-gapdh; ec 1.2.1.13) consists of two types of subunits: gapa and gapb, which are rather similar, except that gapb carries an unique c-terminal sequence extension. here, we report evidence that this sequence extension might be responsible for aggregation and dark inactivation of the enzyme in vivo. recently, it had been demonstrated that upon limited proteolysis of the purified 600 kda enzyme, using the staphylococcus au ... | 1996 | 8814230 |
| function, structure and evolution of fructose-1,6-bisphosphatase. | the hydrolysis of fructose-1,6-bisphosphate to fructose-6-phosphate is a key reaction of carbohydrate metabolism. the enzyme that catalyzes this reaction, fructose-1,6-bisphosphatase, appears to be present in all forms of living organisms. regulation of the enzyme activity, however, occurs by a variety of distinct mechanisms. these include amp inhibition (most sources), cyclic amp-dependent phosphorylation (yeast), and light-dependent activation (chloroplast). in this short review, we have analy ... | 1987 | 8816077 |
| subcellular localization of spinach cysteine synthase isoforms and regulation of their gene expression by nitrogen and sulfur. | subcellular localization and regulation of the spinach (spinacia oleracea) cysteine synthase (o-acetyl-l-serine[thiol]-lyase, ec 4.2.99.8) isoforms (cysa, cysb, and cysc) were determined in transgenic tobacco (nicotiana tabacum) and in spinach cell cultures. the 5' regions of cysb and cysc encoding the chloroplastic (cysb-tp) and the putative mitochondrial (cysc-tp) transit peptide (tp) sequences were fused to a bacterial beta-glucuronidase gene (gus) and expressed in tobacco under the control o ... | 1996 | 8819326 |
| interspecies cross-reactivity of a monoclonal antibody directed against wheat chloroplast fructose-1,6-bisphosphatase. | the primary structure of several chloroplast fructose-1,6-bisphosphatase (cfbpase) was deduced from dna sequences, but only spinach, pea and rapeseed enzymes have been characterized structurally. we analyzed whether cfbpases from different phylogenetic origin contain a common epitope. to this end a dna fragment of 1200 base pairs encoding 338 amino acid residues of wheat cfbpase (38 kda) was cloned in the expression plasmid pgex-1 in frame with the gene coding for glutathione s-transferase (gt) ... | 1996 | 8832098 |
| cloning and molecular analysis of cdnas encoding three sucrose phosphate synthase isoforms from a citrus fruit (citrus unshiu marc.). | three partial cdna clones (psps1, psps2 and psps3) encoding sucrose phosphate synthases (sps) were isolated by reverse transcription (rt)-pcr using first-strand cdna prepared from the leaf or fruit of citrus (citrus unshiu marc.). the nucleotide and deduced amino acid sequences of the three clones showed significant similarities to sps previously isolated in other plants. a full-length, cdna clone, citsps1, was isolated from a fruit (juice sacs and pulp segment) cdna library using one (psps1) of ... | 1996 | 8842155 |
| changes in microbial populations on fresh cut spinach. | the microbial populations found on fresh-cut spinach leaves that were stored in gas permeable bags at 10 degrees c for 12 days were examined and identified. the microorganisms consisted of mesophilic aerobic bacteria, psychrotrophic bacteria, pseudomonadaceae, enterobacteriaceae, micrococcaceae, lactic acid bacteria and yeasts. populations of mesophiles, psychrotrophs, pseudomonadaceae and enterobacteriaceae increased sharply during the storage period. the initial populations were 10(7), 10(6), ... | 1996 | 8880301 |
| x-ray structure of the ferredoxin:nadp+ reductase from the cyanobacterium anabaena pcc 7119 at 1.8 a resolution, and crystallographic studies of nadp+ binding at 2.25 a resolution. | the crystal structure of the ferredoxin:nadp+ reductase (fnr) from the cyanobacterium anabaena pcc 7119 has been determined at 2.6 a resolution by multiple isomorphous replacement and refined using 15.0 a to 1.8 a data, collected at 4 degrees c, to an r-factor of 0.172. the model includes 303 residues, the flavin adenine dinucleotide cofactor (fad), one sulfate ion located at the putative nadp+ binding site and 328 water molecule sites. the structure of anabaena fnr, including fad, a network of ... | 1996 | 8890910 |
| introduction and expression of foreign dna in isolated spinach chloroplasts by electroporation. | an electroporation-mediated method for the study of foreign gene expression within chloroplasts has been developed. the chloroplast expression vector phd203-gus, which consists of coding regions for beta-glucuronidase (gus) and chloramphenicol acetyltransferase (cat) separated by a double psba promoter fragment from pea (in opposite orientation) was electroporated into spinach chloroplasts and the transient gene expression was examined. conditions for the expression of the reporter genes have be ... | 1996 | 8893549 |
| amino acid sequence of the maize ferredoxin:thioredoxin reductase variable subunit. | the ferredoxin:thioredoxin reductase (ftr) is the essential enzyme of the light dependent regulatory system controlling enzyme activities in oxygenic, photosynthetic cells. this protein is composed of two dissimilar subunits, a catalytic subunit containing a [4fe-4s] cluster and a redox-active disulfide bridge as the active site, and a variable subunit, whose function is not known yet. whereas size and primary structure of the catalytic subunit from different organisms seem to be well conserved, ... | 1996 | 8898896 |
| purification and partial characterization of two thioredoxins from streptomyces aureofaciens. | thioredoxins are low molecular weight proteins, which participate in a wide spectrum of biochemical reactions. two thioredoxins from streptomyces aureofaciens 3239 have been purified to homogeneity by a sequence of chromatography steps including chromatography on sephacryl s-300, phenyl sepharose cl 4b and monoq hr 5/5. thioredoxin activity clearly separates into two protein fractions on monoq hr 5/5 chromatography. molecular weights determined by chromatography on superose 12 hr 10/30 and sodiu ... | 1996 | 8908358 |
| identification, characterization, and molecular cloning of a homologue of the bacterial ftsh protease in chloroplasts of higher plants. | in an attempt to identify and characterize chloroplast proteases, we performed an immunological analysis of chloroplasts using an antibody against escherichia coli ftsh protease, which is an atp-dependent metalloprotease bound to the cytoplasmic membrane. a cross-reacting protein of 78 kda was found in the thylakoid membrane of spinach, but not in the soluble stromal fraction. alkali and high salt washes, as well as trypsin treatment of thylakoid membranes, suggest that the chloroplastic ftsh pr ... | 1996 | 8910594 |
| evidence that the plastid signal and light operate via the same cis-acting elements in the promoters of nuclear genes for plastid proteins. | nuclear-encoded genes for proteins of the photosynthetic machinery represent a particular subset of genes. their expression is cooperatively stimulated by discrete factors including the developmental stage of plastids and light. we have analyzed in transgenic tobacco the plastid- and light-dependent expression of a series of 5' promoter deletions of various nuclear genes from spinach, of fusions of defined promoter segments with the 90-bp 35s rna camv minimal promoter, as well as with mutations ... | 1996 | 8917305 |
| the bioavailability of magnesium in spinach and the effect of oxalic acid on magnesium utilization examined in diets of magnesium-deficient rats. | spinach was evaluated for its bioavailability of magnesium in the experiment with magnesium-deficient rats. the effect of oxalic acid on absorption of dietary magnesium was also examined in the same experiment. after there were significant differences in the body weight of the rats between the control group and the magnesium-deficient group, and after the number of dead rats increased, the magnesium-deficient rats were divided into six groups. they were pair-fed for 8 days on the magnesium-defic ... | 1995 | 8926539 |
| high-level expression, purification, and crystallization of recombinant spinach glycolate oxidase in escherichia coli. | glycolate oxidase is a flavin-dependent enzyme in the photorespiratory pathway in plants. here we report the heterologous expression of glycolate oxidase in escherichia coli and an isolation procedure which results in 4 mg pure protein per gram cell paste in only 1.5 days. this corresponds to a more than 50-fold improvement in yield compared to previously reported expression systems. the purified recombinant protein can be crystallized easily, and the crystals are isomorphous to those obtained f ... | 1996 | 8936590 |
| characterization and crystallization of the lumen side domain of the chloroplast rieske iron-sulfur protein. | a soluble, 139-residue cooh-terminal polypeptide fragment of the rieske iron-sulfur protein of the cytochrome b6f complex from spinach chloroplasts was obtained by limited proteolysis of the complex and a two-step chromatography purification protocol. the purified rieske iron-sulfur protein fragment was characterized by: (i) a single nh2-terminal sequence, nh2-phe-val-pro-pro-gly-gly, starting with residue 41 of the intact rieske protein; (ii) a single molecular weight species determined by mass ... | 1996 | 8940143 |
| glutamate 94 of [2fe-2s]-ferredoxins is important for efficient electron transfer in the 1:1 complex formed with ferredoxin-glutamate synthase (glts) from synechocystis sp. pcc 6803. | we have analyzed the role of critical amino acid residues involved in the interaction between ferredoxin and ferredoxin-glutamate synthase (gogat) encoded by the glts gene from the cyanobacterium synechocystis sp. pcc 6803. our results indicated that the glutamate 94 residue of anabaena 7120 ferredoxin (= e92 of the synechocystis 6803 ferredoxin) was necessary for an efficient electron transfer to gogat comparable to ferredoxin:nadp-reductase, nitrite reductase and nitrate reductase [schmitz and ... | 1996 | 8950376 |
| is e37, a major polypeptide of the inner membrane from plastid envelope, an s-adenosyl methionine-dependent methyltransferase? | using antibodies raised against e37, one of the major polypeptides of the inner membrane from the chloroplast envelope, it has been demonstrated that a single immunologically related polypeptide was present in total protein extracts from various higher plants (monocots and dicots), in photosynthetic and non-photosynthetic tissues from young spinach plantlets, as well as in the cytoplasmic membrane from the cyanobacteria synechococcus. this ubiquitous distribution of e37 strongly suggests that th ... | 1996 | 8953251 |
| intron sequences are involved in the plastid- and light-dependent expression of the spinach psad gene. | plastid- and light-regulated expression of the spinach psad gene in transgenic tobacco requires sequences downstream of the transcription start site, sand promoter sequences alone are not sufficient to respond to these stimuli. the spinach psad mrna level in transgenic tobacco is still plastid- and light-responsive when the expression of the intron-containing transcription unit is driven by the 35s rna camv promoter indicating that psad contains (a) gene-internal control element(s). if the genom ... | 1996 | 8953253 |
| studies on protein processing for membrane-bound spinach leaf mitochondrial processing peptidase integrated into the cytochrome bc1 complex and the soluble rat liver matrix mitochondrial processing peptidase. | the plant mitochondrial processing peptidase (mpp) that catalyses the cleavage of the presequences from precursor proteins during or after protein import is a membrane-bound enzyme that constitutes an integral part of the bc1 complex of the respiratory chain. in contrast, mpp from mammals is soluble in the matrix space and does not form part of the respiratory chain. in the present study, we have compared the substrate specificity of the isolated spinach leaf bc1/mpp with rat liver mpp using syn ... | 1996 | 8954161 |
| the mechanism of gt element-mediated cell type-specific transcriptional control. | promoter studies have revealed that sequences related to the gt-1 binding site, known as gt elements, are conserved in plant nuclear genes of diverse functions. in this work, we addressed the issue of whether gt elements are involved in cell type-specific transcriptional regulation. we found that the inactivation of gt-1 site-mediated transcription in roots is correlated with the absence of the gt-1 binding activity in root extracts. in addition, the mutation of the related gt-1 (from the pea rb ... | 1996 | 8955086 |
| cross-linking of engineered subunit delta to (alphabeta)3 in chloroplast f-atpase. | ser --> cys mutations were introduced into subunit delta of spinach chloroplast f0f1-atpase (cf0cf1) by site-directed mutagenesis. the engineered delta subunits were overexpressed in escherichia coli, purified, and reassembled with spinach chloroplast f1-atpase (cf1) lacking the delta subunit (cf1(-delta)). by modification with eosin-5-maleimide, it was shown that residues 10, 57, 82, 160, and 166 were solvent-accessible in isolated cf1 and all but residue 166 also in membrane-bound cf0cf1. modi ... | 1996 | 8955107 |
| identification of a chloroplast coenzyme a-binding protein related to the peroxisomal thiolases. | a 30-kd coenzyme a (coa)-binding protein was isolated from spinach (spinacea oleracea) chloroplast soluble extracts using affinity chromatography under conditions in which 95% of the total protein was excluded. the 30-kd protein contains an eight-amino-acid sequence, dvrlyyga, that is identical to a region in a 36-kd protein of unknown function that is encoded by a kiwifruit (actinidia deliciosa) cdna. southern blotting also detected a spinach gene that is related to the kiwifruit cdna. the kiwi ... | 1996 | 8972603 |
| molecular characterization of transketolase (ec 2.2.1.1) active in the calvin cycle of spinach chloroplasts. | a cdna encoding the calvin cycle enzyme transketolase (tkl; ec 2.2.1.1) was isolated from sorghum bicolor via subtractive differential hybridization, and used to isolate several full-length cdna clones for this enzyme from spinach. functional identity of the encoded mature subunit was shown by an 8.6-fold increase of tkl activity upon induction of escherichia coli cells that overexpress the spinach tkl subunit under the control of the bacteriophage t7 promoter. chloroplast localization of the cl ... | 1996 | 8980496 |
| functional studies of chloroplast glyceraldehyde-3-phosphate dehydrogenase subunits a and b expressed in escherichia coli: formation of highly active a4 and b4 homotetramers and evidence that aggregation of the b4 complex is mediated by the b subunit carboxy terminus. | chloroplast glyceraldehyde-3-phosphate dehydrogenase (phosphorylating, e.c. 1.2.1.13) (gapdh) of higher plants exists as an a2b2 heterotetramer that catalyses the reductive step of the calvin cycle. in dark chloroplasts the enzyme exhibits a molecular mass of 600 kda, whereas in illuminated chloroplasts the molecular mass is altered in favor of the more active 150 kda form. we have expressed in escherichia coli proteins corresponding to the mature a and b subunits of spinach chloroplast gapdh (g ... | 1996 | 8980499 |
| cp12: a small nuclear-encoded chloroplast protein provides novel insights into higher-plant gapdh evolution. | higher-plant chloroplast nad(p)-glyceraldehyde 3-phosphate dehydrogenase (nad(p)-gapdh; ec 1.2.1.13) is composed of two different nuclear-encoded subunits, gapa and gapb, forming the highly active heterotetrameric a2b2 enzyme. the main difference between these two subunits is a c-terminal extension of about 30 amino acid residues of gapb. we present cdna clones for a nuclear-encoded chloroplast protein from pea, spinach and tobacco, which we have named cp12. the mature protein consists of only 7 ... | 1996 | 8980547 |
| molecular cloning of a cdna encoding 3-ketoacyl-acyl carrier protein synthase iii from leek. | 3-ketoacyl-acyl carrier protein synthase iii (kas iii) catalyzes the initial condensation of malonyl-acyl carrier protein (acp) with acetyl-coa in plant and bacterial fatty acid biosynthesis. the first cdna clone encoding kas iii from a monocot is reported here. a cdna clone was isolated from a leek epidermal cdna library by screening with spinach and arabidopsis heterologous probes from kas iii cdna clones. when expressed in escherichia coli, the cloned enzyme was able to catalyze the expected ... | 1996 | 8982066 |
| recombinant hansenula polymorpha as a biocatalyst: coexpression of the spinach glycolate oxidase (go) and the s. cerevisiae catalase t (ctt1) gene. | the methylotrophic yeast hansenula polymorpha has been developed as an efficient production system for heterologous proteins. the system offers the possibility to cointegrate heterologous genes in anticipated fixed copy numbers into the chromosome. as a consequence co-production of different proteins in stoichiometric ratios can be envisaged. this provides options to design this yeast as an industrial biocatalyst in procedures where several enzymes are required for the efficient conversion of a ... | 1996 | 8987534 |
| cloning of the gene for monogalactosyldiacylglycerol synthase and its evolutionary origin. | monogalactosyldiacylglycerol (mgdg) synthase (udpgalactose:1,2-diacylglycerol 3-beta-d-galactosyltransferase; ec 2.4.1.46) catalyzes formation of mgdg, a major structural lipid of chloroplast. we cloned a cdna for the synthase from cucumber cdna library. the full-length cdna clone was 2142 bp, and it contains a 1575-bp open reading frame encoding 525 aa. the open reading frame consists of the regions for a mature protein (422 aa; mr of 46,552) and transit peptide to chloroplast (103 aa). althoug ... | 1997 | 8990209 |
| the reaction mechanism of phosphomannomutase in plants. | the enzyme phosphomannomutase catalyzes the interconversion of mannose-1-phosphate (man-1-p) and mannose-6-phosphate (man-6-p). in mammalian cells the enzyme has to be activated by transfer of a phosphate group from a sugar-1.6-p2 (guha, s.k. and rose, z.b. (1985) arch. biochem. biophys. 243, 168). in contrast, in the red alga galdieria sulphuraria the co-substrate (man-1.6-p2 or glc-1.6-p2) is converted to the corresponding sugar monophosphate while the substrate is converted to the sugar bisph ... | 1997 | 9003801 |
| plant 21d7 protein, a nuclear antigen associated with cell division, is a component of the 26s proteasome. | previously, we cloned a carrot (daucus carota l.) cdna encoding a 45-kd protein, 21d7, located in the nuclei of proliferating cells. the 21d7 protein is similar to the partial sequence of a regulatory subunit of the bovine 26s proteasome, p58 (g. demartino, c.r. moomaw, o.p. zagnitko, r.j. proske, m. chu-ping, s.j. afendis, j.c. swaffield, c.a. slaughter [1994] j biol chem 269: 20878-20884) and to the deduced sequence encoded by the saccharomyces cerevisiae gene sun2 (m. kawamura, k. kominami, j ... | 1997 | 9008397 |
| residue glu-91 of chlamydomonas reinhardtii ferredoxin is essential for electron transfer to ferredoxin-thioredoxin reductase. | the [2fe-2s] soluble ferredoxin from chlamydomonas reinhardtii was mutated by site directed mutagenesis, using pcr and the expression plasmid pet-fd as a template. the recombinant mutated proteins were purified to homogeneity and tested in the activation of nadp-malate dehydrogenase, a light dependent reaction in which ferredoxin thioredoxin reductase (ftr) and thioredoxin are involved. the mutation of residue glu-91 (e92 in spinach, e94 in anabaena) alone, either to gln (e91q) or to lys (e91k), ... | 1997 | 9009217 |
| substrate specificity modification of the stromal glycerol-3-phosphate acyltransferase. | the stromal glycerol-3-phosphate acyltransferases (gpats; ec 2.3.1.15) from spinach (spinacia oleracea) and squash (cucurbita moschata) were expressed in escherichia coli and their activities with palmitoyl-coa and oleoyl-coa compared. the gpat from squash, a chilling-sensitive plant, was found to have the greatest difference in activities between the two substrates, using palmitoyl-coa over three times faster than oleoyl-coa. in contrast, the enzyme from spinach, a chilling-tolerant plant, pref ... | 1997 | 9016814 |
| characterization of a novel eukaryotic atp/adp translocator located in the plastid envelope of arabidopsis thaliana l. | recently, we have sequenced a cdna clone from arabidopsis thaliana l. encoding a novel putative atp/adp translocator (aatp1). here, we demonstrate that the radioactively labeled aatp1 precursor protein, synthesized in vitro, is targeted to envelope membranes of isolated spinach chloroplasts. antibodies raised against a synthetic peptide of aatp1 recognized a single polypeptide of about 62 kda in chloroplast inner envelope preparations. the cdna coding for the aatp1 protein was functionally expre ... | 1997 | 9025303 |
| isozymes of superoxide dismutase from aloe vera. | extracts from the parenchymatous leaf gel and the rind of the aloe vera plant (aloe barbadensis miller) were shown to contain seven electrophoretically-identifiable superoxide dismutases (sods). the chromatographic elution profiles and the migration of these bands on native polyacrylamide gel electrophoresis (page), for both the gel and rind, are quite similar. two of these seven activities are insensitive to cyanide treatment, suggesting that they are mangano-sods. the other five activities are ... | 1996 | 9030888 |
| molecular cloning, characterization and expression of cdna encoding phosphoserine aminotransferase involved in phosphorylated pathway of serine biosynthesis from spinach. | phosphoserine aminotransferase (psa) catalyzes the conversion of phosphohydroxypyruvate to phosphoserine in the phosphorylated pathway of serine biosynthesis. a cdna clone encoding psa was isolated from the cdna library of spinach (spinacia oleracea l.) green leaves. determination of the nucleotide sequence revealed the presence of an open reading frame encoding 430 amino acids, exhibiting 38-50% homology with the amino acid sequences of bacterial, yeast and animal psa. it contains an n-terminal ... | 1997 | 9037153 |
| structural homology of spinach acyl carrier protein and escherichia coli acyl carrier protein based on nmr data. | acyl carrier proteins (acps) from spinach and from escherichia coli have been used to demonstrate the utility of proton nmr for comparison of homologous structures. the structure of e. coli acp had been previously determined and modeled as a rapid equilibrium among multiple conformational forms (kim and prestegard, biochemistry 28:8792-8797, 1989). spinach acp showed two slowly exchanging forms and could be manipulated into one form for structural study. here we compare this single form to postu ... | 1997 | 9037718 |
| side reactions catalyzed by ribulose-bisphosphate carboxylase in the presence and absence of small subunits. | the large subunit core of ribulose-bisphosphate carboxylase from synechococcus pcc 6301 expressed in escherichia coli in the absence of its small subunits retains a trace of carboxylase activity (about 1% of the kcat of the holoenzyme) (andrews, t. j (1988) j. biol. chem. 263, 12213-12219). during steady-state catalysis at substrate saturation, this residual activity diverted approximately 10% of the reaction flux to 1-deoxy-d-glycero-2,3-pentodiulose-5-phosphate as a result of beta elimination ... | 1997 | 9038145 |
| some characteristics of cytochrome f in the cyanobacterium phormidium laminosum: its sequence and charge properties in the reaction with plastocyanin. | part of the petca operon was cloned and the sequence of the cytochrome f gene from the moderately thermophilic cyanobacterium phormidium laminosum determined. a partial sequence of the petc gene encoding the rieske iron-sulphur protein was also obtained. the cytochrome f gene encodes a mature protein of 385 residues and a leader sequence of 45 residues. the mature protein contains several acidic or neutral residues corresponding to basic residues in the turnip protein. some of the latter are tho ... | 1996 | 8856106 |
| kinetic evidence for protein complexes between thioredoxin and nadp-malate dehydrogenase and presence of a thioredoxin binding site at the n-terminus of the enzyme. | the kinetics of activation of nadp-malate dehydrogenase (mdh; ec 1.1.1.82) from soybean and spinach leaves by the chloroplast thioredoxins isolated from the same plants, by the corresponding storage forms of the soybean chloroplast thioredoxins from soybean seeds, and by the bacterial escherichia coli thioredoxin have been studied. the hill equation has been applied to evaluate the saturation kinetics. the observed variable thioredoxin saturation characteristics (vmax 0.37-14.5 mumol nadph min-1 ... | 1996 | 8856084 |
| analysis of the native forms of the 90 kda heat shock protein (hsp90) in plant cytosolic extracts. | a polyclonal antibody, r2, was raised against a fusion protein consisting of a portion of plant hsp90 fused to the trpe protein of escherichia coli. this antibody was found to be specific towards plant hsp90, showing little or no cross-reactivity with mouse and human hsp90 proteins. the r2 antibody identified an 83 kda protein as the hsp90 homologue in cytosolic extracts of several dicot and monocot plants. two-dimensional gel electrophoresis indicated that at least two different isoforms of hsp ... | 1997 | 9049266 |
| two-dimensional electrophoresis of membrane proteins: a current challenge for immobilized ph gradients. | membrane proteins were separated by high resolution two-dimensional (2-d) electrophoresis. on isoelectric focusing (ief) with immobilized ph gradients severe protein losses in the resulting 2-d map were observed when compared with carrier ampholyte-based ief. this has been noticed for two different biological systems, namely the chloroplast envelope of spinach and the endocytic vesicles from dictyostelium discoideum. the possible mechanisms of these losses on immobilized ph gradients are discuss ... | 1997 | 9059834 |
| comparison of metabolic effects of vegetables and teas with colorectal proliferation and with tumour development in dmh-treated f344 rats. | the aim of this study was to screen potentially chemopreventive vegetables and teas for their effects as human dietary components for the colorectal epithelium and also to seek biomarkers of preventive efficacy. groups of f344 rats were adapted to a human basal diet supplemented with vegetables or teas, having known contents of glucosinolates, polyphenols and anti-oxidants. both inductions and suppressions were found for overall glutathione s-transferase (gst) and quinone reductase activities. t ... | 1997 | 9103311 |
| gibberellin biosynthesis from gibberellin a12-aldehyde in endosperm and embryos of marah macrocarpus. | soluble enzyme preparations from embryos and endosperm of marah macrocarpus (previously echinocystis macrocarpa) were incubated with [14c4]gibberellin(ga)12-aldehyde, [14c4]ga12, [14c1] ga9, 2,3-didehydro[14c1]ga9, [14c1]ga20, and [17-13c, 3h]ga5. embryo preparations converted ga12-aldehyde, ga12, and ga9 to ga4 and ga7; 2,3-didehydroga9 to ga7; ga5 to ga3; and ga20 (incompletely) to ga1 and ga60, but not to ga3. endosperm preparations converted ga12-aldehyde and ga12 to ga15, ga24, and ga9, but ... | 1997 | 9112781 |
| prh75, a new nucleus-localized member of the dead-box protein family from higher plants. | the putative rna helicases of the dead-box protein family are involved in pre-mrna splicing, rrna maturation, ribosome assembly, and translation. members of this protein family have been identified in organisms from escherichia coli to humans, but except for the translation initiation factor 4a, there have been no reports on the characterization of other dead-box proteins from plants. here we report on a novel member of the dead-box protein family, the plant rna helicase 75 (prh75). prh75 is loc ... | 1997 | 9121476 |
| organ-specific transcription of the rrn operon in spinach plastids. | the spinach rrn operon is used as a model system to study transcriptional regulation in higher plant photosynthetic and non-photosynthetic plastids. we performed capping experiments to determine whether p1, pc, or p2 promoters are employed for rrn transcription start sites in cotyledon and root tissues. by using a new method of analysis of capped rna we demonstrate for the first time that 1) in both organs the rrn operon is expressed in a constitutive manner by cotranscription with the preceding ... | 1997 | 9153218 |
| composition and primary structure of the f1f0 atp synthase from the obligately anaerobic bacterium clostridium thermoaceticum. | the subunit composition and primary structure of the proton-translocating f1f0 atp synthase have been determined in clostridium thermoaceticum. the isolated enzyme has a subunit composition identical to that of the f1f0 atp synthase purified from clostridium thermoautotrophicum (a. das, d. m. ivey, and l. g. ljungdahl, j. bacteriol. 179:1714-1720, 1997), both having six different polypeptides. the molecular masses of the six subunits were 60, 50, 32, 17, 19, and 8 kda, and they were identified a ... | 1997 | 9171425 |
| role of psii-l protein (psbl gene product) on the electron transfer in photosystem ii complex. 1. over-production of wild-type and mutant versions of psii-l protein and reconstitution into the psii core complex. | to establish a system for over-production of psii-l protein which is a component of photosystem ii (psii) complex, a plasmid designated as pmal-psbl was constructed and expressed in escherichia coli jm109. a fusion protein of psii-l and maltose-binding proteins (53 kda on sds-page) was accumulated in e. coli cells to a level of 10% of the total protein upon isopropyl-beta-d-thiogalactopyranoside (iptg) induction. the carboxyl-terminal part of 5.0 kda was cleaved from the fusion protein and purif ... | 1997 | 9177321 |
| stimulation of spinach (spinacia oleracea) chloroplast fructose-1,6-bisphosphatase by mercuric ions. | chloroplast fructose-1,6-bisphosphatase can exist in an active reduced form or a less active oxidised form. oxidised fructose bisphosphatase from spinach (spinacia oleracea) could be stimulated up to many hundred-fold by 0.1 mm hgcl2 whereas fructose bisphosphatases from rabbit, yeast, a non-chloroplast enzyme from spinach and the reduced chloroplast enzyme were only inhibited by hgcl2. stimulation of the enzyme was maximal at ph 8.0 and low magnesium concentrations where the oxidised enzyme nor ... | 1997 | 9180262 |
| purification and characterization of a fusion protein of plant acetohydroxy acid synthase and acetohydroxy acid isomeroreductase. | the nucleotide sequence coding for the arabidopsis thaliana acetohydroxy acid synthase was genetically fused in frame with the nucleotide sequence coding for the spinacia oleracea acetohydroxy acid isomeroreductase and expressed in escherichia coli. this construction allowed the production of large amounts of soluble fusion protein. the pure chimeric enzyme exhibits high acetohydroxy acid synthase and acetohydroxy acid isomeroreductase specific activities. fusion and native enzymes exhibit simil ... | 1997 | 9187358 |
| specificity for activase is changed by a pro-89 to arg substitution in the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase. | tobacco activase does not markedly facilitate the activation of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco, ec 4.1.1. 39) from non-solanaceae species, including the green alga chlamydomonas reinhardtii. to examine the basis of this specificity, we focused on two exposed residues in the large subunit of rubisco that are unique to the solanaceae proteins. by employing in vitro mutagenesis and chloroplast transformation, p89r and k356q substitutions were separately made in the chlamyd ... | 1997 | 9202018 |
| antigenotoxic activity of natural chlorophylls. | chlorophyllin, a man-made water-soluble form of chlorophyll, is a focus of intensive studies from many laboratories for its antimutagenic and anticarcinogenic properties. natural chlorophylls, in contrast, have been little studied in this regard. since yellow-green vegetables are implicated to be protective against human cancers by epidemiological studies, it is important to explore the antigenotoxic properties of natural chlorophylls. previously, we reported that a chlorophyll sample prepared f ... | 1997 | 9202743 |
| inhibition of the mutagenicity of 2-nitrofluorene, 3-nitrofluoranthene and 1-nitropyrene by vitamins, porphyrins and related compounds, and vegetable and fruit juices and solvent extracts. | when 21 vitamins including related compounds haemin, chlorophyllin, chlorophyll, biliverdin and bilirubin, as well as juices from five fruits and 25 vegetables and solvent extracts from the residues of fruits and vegetables were tested for their antimutagenic potencies with respect to mutagenicity induced by 2-nitrofluorene (2-nf), 3-nitrofluoranthene (3-nfa) and 1-nitropyrene(1-np) in salmonella typhimurium ta98 the following results were obtained. the tetracyclic nitroarenes 3-nfa and 1-np wer ... | 1997 | 9207899 |
| diet and stomach cancer in korea. | stomach cancer is the most prevalent malignant neoplasm in korea. as of 1991-1992 in seoul, the cumulative rates reported for the age span 0-74 were 7.6% in males and 3.1% in females. a recent case-control study reported that several food items and cooking methods are associated with increased or decreased risk of stomach cancer among koreans. an increased risk of stomach cancer was noted among people who frequently consume broiled meats and fishes, salted side dishes (salted/fermented fish prod ... | 1997 | 9209012 |
| cucumber chloroplast trnl(caa) gene: nucleotide sequence and in vivo expression analysis in etiolated cucumber seedlings treated with benzyladenine and light. | the nucleotide sequence of a 714 bp bamhi-ecori fragment of cucumber chloroplast dna was determined. the fragment contained a gene for trna(leu) together with its flanking regions. the trnl(caa) gene sequence is about 99% in similarity to broad bean, cauliflower, maize, spinach and tobacco corresponding genes. the relative expression level of the gene was determined by northern (trna) gel blot and northern (total cellular rna) slot-blot analyses using the trnl gene probe in 6-day old etiolated c ... | 1996 | 9219428 |
| characterization and expression of two members of the s-adenosylmethionine decarboxylase gene family in carnation flower. | s-adenosylmethionine decarboxylase (samdc; ec 4.1.4.50) is one of the key enzymes in polyamine biosynthesis, and the product of its catalytic reaction, decarboxylated s-adenosylmethionine (dcsam), serves as an aminopropyl donor in the biosynthesis of spermidine and spermine. in order to provide information on the structure and regulation of samdc, we have isolated and sequenced two different samdc cdna clones from carnation petals. the nucleotide sequences of csdc9 and csdc16 show 78.3% identity ... | 1997 | 9225849 |
| footprinting of the spinach nitrite reductase gene promoter reveals the preservation of nitrate regulatory elements between fungi and higher plants. | nitrite reductase (nir) is the second enzyme in the nitrate assimilatory pathway reducing nitrite to ammonium. the expression of the nir gene is induced upon the addition of nitrate. in an earlier study, a 130 bp upstream region of the spinach nir gene promoter, located between -330 to - 200, was shown to be necessary for nitrate induction of beta-glucuronidase (gus) expression in tissue-specific manner in transgenic tobacco plant [28]. to further delineate the cis-acting elements involved in ni ... | 1997 | 9225857 |
| the complete sequence of the genomic rnas of spinach latent virus. | we describe the sequence for the complete genome of spinach latent virus (splv). comparisons of this genome with that of the only other complete genome described for a species within the genus ilarvirus (citrus leaf rugose virus-cilrv) indicate that while there are marked differences between the rna 3 of the two viruses, their respective rnas 1 and 2 share many similarities. however, the putative 2a protein of splv contains a c2h2 type "zinc finger"-like motif located towards the carboxy termina ... | 1997 | 9229009 |
| structural analysis of photosystem ii: comparative study of cyanobacterial and higher plant photosystem ii complexes | oxygen evolving photosystem ii (psii-oec) complexes and psii core complexes were isolated from spinach and the thermophilic cyanobacterium synechococcus sp. od24 and characterized by gel electrophoresis, immunoblotting, and absorbance spectroscopy. the mass of the core complexes was determined by scanning transmission electron microscopy (stem) and found to be 281 ± 65 kda for spinach and 313 ± 52 kda for synechococcus sp. od24. the mass of the spinach psii-oec complex was 327 &plu ... | 1997 | 9245767 |
| engineering pichia pastoris for biocatalysis: co-production of two active enzymes. | high levels of active glycolate oxidase from spinach (go) and active catalase t from saccharomyces cerevisiae (catt) have been co-produced in the methylotrophic yeast pichia pastoris (pp). in sequential rounds of transformation using two selectable markers, multiple copies of the genes encoding go and catt were integrated into the pp chromosome under control of the methanol inducible alcohol oxidase i promoter, resulting in a strain designated msp8.6. msp8.6 is a second-generation biocatalyst us ... | 1997 | 9272859 |
| high-yield expression of pea thioredoxin m and assessment of its efficiency in chloroplast fructose-1,6-bisphosphatase activation. | a cdna clone encoding pea (pisum sativum l.) chloroplast thioredoxin (trx) m and its transit peptide were isolated from a pea cdna library. its deduced amino acid sequence showed 70% homology with spinach (spinacia oleracea l.) trx m and 25% homology with trx f from pea and spinach. after subcloning in the ndel-bamhi sites of pet-12a, the recombinant supplied 20 mg trx m/l. escherichia coli culture. this protein had 108 amino acids and was 12,000 d, which is identical to the pea leaf native prot ... | 1997 | 9276945 |
| s2f, a leaf-specific trans-acting factor, binds to a novel cis-acting element and differentially activates the rpl21 gene. | tissue-specific factors control the differential expression of nuclear genes encoding plastid proteins. to identify some of these factors, the light-independent spinach rpl21 gene encoding the plastid ribosomal protein l21 was chosen as a model. the rpl21 promoter organization was defined by transient and stable transfections of rpl21 promoter deletion mutants fused to a reporter gene. the following results were obtained. (1) we identified a strong core promoter, spanning the transcription start ... | 1997 | 9286115 |
| dietary modification of human macular pigment density. | the retinal carotenoids lutein (l) and zeaxanthin (z) that form the macular pigment (mp) may help to prevent neovascular age-related macular degeneration. the purpose of this study was to determine whether mp density in the retina could be raised by increasing dietary intake of l and z from foods. | 1997 | 9286268 |
| the regulatory functions of the gamma and epsilon subunits from chloroplast cf1 are transferred to the core complex, alpha3beta3, from thermophilic bacterial f1. | the expression plasmids for the subunit gamma (gamma(c)) and the subunit epsilon (epsilon(c)) of chloroplast coupling factor (cf1) from spinach were constructed, and the desired proteins were expressed in escherichia coli. both expressed subunits were obtained as inclusion bodies. when recombinant gamma(c) was mixed with recombinant alpha and beta subunits of f1 from thermophilic bacillus ps3 (tf1), a chimeric subunit complex (alpha3beta3gamma(c)) was reconstituted and it showed significant atp ... | 1997 | 9288943 |
| induction of genes encoding plastidic phosphorylase from spinach (spinacia oleracea l.) and potato (solanum tuberosum l.) by exogenously supplied carbohydrates in excised leaf discs. | a full-length cdna encoding plastidic phosphorylase (pho1, ec 2.4.1.1) from spinach (spinacia oleracea l.) has been isolated. analysis of the deduced protein sequence revealed considerable homologies with the corresponding proteins from other plants, animals and prokaryotes. escherichia coli cells carrying the entire cdna for pho1 expressed an active phosphorylase, which resembled the properties of the plastidic isozyme of spinach with respect to its low affinity to glycogen. expression of pho1 ... | 1997 | 9299793 |
| specific interaction of the [2fe-2s] ferredoxin from clostridium pasteurianum with the nitrogenase mofe protein. | putative physiological partners of the [2fe-2s] ferredoxin from clostridium pasteurianum have been searched by running crude soluble extracts of this bacterium through an affinity column to which the [2fe-2s] ferredoxin had been covalently bound. subsequent washing of the column with buffers of increasing ionic strength revealed a strong and specific interaction of the ferredoxin with the mofe protein of nitrogenase. this interaction was further investigated by performing cross-linking experimen ... | 1997 | 9305970 |
| effects of codon usage and vector-host combinations on the expression of spinach plastocyanin in escherichia coli. | spinach plastocyanin has been expressed in escherichia coli and exported to the periplasmic space. the effects of codon usage, expression system, growth length, and temperature on expression levels in lb medium were investigated. a stretch of codons, rare in e. coli, was identified and replaced with highly expressed codons, increasing the yield by at least 20%. plastocyanin was more efficiently expressed under the t7 promoter than under the lac promoter. maximum yields were obtained at 37 degree ... | 1997 | 9325134 |
| consumption of vegetables reduces genetic damage in humans: first results of a human intervention trial with carotenoid-rich foods. | a human intervention study with vegetable products has been performed in twenty three healthy, non smoking males aged 27-40. it was the aim of the study to assess whether consumption of vegetables containing different carotenoids could protect against dna damage and oxidative dna damage. the subjects consumed their normal diets, but abstained from vegetables high in carotenoids throughout the study period. after a 2 week depletion period, they received daily 330 ml tomato juice with 40 mg lycope ... | 1997 | 9328185 |
| purification and characterization of thylakoid membrane-bound inorganic pyrophosphatase from spinacia oleracia l. | an inorganic pyrophosphatase (ppase) was purified from thylakoid membrane of spinach leaves to electrophoretic purity by methods including detergent solubilization, ammonium sulfate fractionation, and successive chromatographic techniques. current protocol yielded about 10% recovery of total activity with a 30-fold purification. the specific activity of the purified enzyme was approximately 400 micromol ppi consumed/mg protein x h. this enzyme is a monomer with a molecular mass of 55 kda. severa ... | 1997 | 9328290 |
| recombinant two-iron rubredoxin of pseudomonas oleovorans: overexpression, purification and characterization by optical, cd and 113cd nmr spectroscopies. | the gene (alk g) encoding the two-iron rubredoxin of pseudomonas oleovorans was amplified from genomic dna by pcr and subcloned into the expression vector pkk223-3. the vector directed the high-level production of rubredoxin in escherichia coli. a simple three-step procedure was used to purify recombinant rubredoxin in the 1fe form. 1fe-rubredoxin was readily converted to the 2fe, apoprotein and cadmium forms after precipitation with trichloroacetic acid and resolubilization in the presence or a ... | 1997 | 9359843 |
| cross-linking of chloroplast f0f1-atpase subunit epsilon to gamma without effect on activity. epsilon and gamma are parts of the rotor. | cys residues were directed into positions 17, 28, 41 and 85 of a cys6-->ser mutant of subunit epsilon of spinach chloroplast f0f1 atp synthase. wild-type and engineered epsilon were expressed in escherichia coli, purified in the presence of urea, refolded and reassembled with spinach chloroplast f1 lacking the epsilon subunit [f1(-epsilon)]. cys-containing epsilon variants were modified with a sulfhydryl-reactive photolabile cross-linker. photocross-linking of epsilon to f1(-epsilon) yielded the ... | 1997 | 9363764 |
| transport of ctpa protein from the cyanobacterium synechocystis 6803 across the thylakoid membrane in chloroplasts. | the ctpa protein in the cyanobacterium synechocystis 6803 is a c-terminal processing protease that is essential for the assembly of the manganese cluster of the photosystem ii complex. when fused to different chloroplast-targeting transit peptides, ctpa can be imported into isolated spinach chloroplasts and is subsequently translocated into the thylakoid lumen. thylakoid transport is mediated by the cyanobacterial signal peptide which demonstrates that the protein transport machinery in thylakoi ... | 1997 | 9370359 |
| fourier transform infrared difference spectroscopy of photosystem ii tyrosine d using site-directed mutagenesis and specific isotope labeling. | tyrosine d (tyrd), a side path electron carrier of photosystem ii (ps ii), has been studied by light-induced fourier transform infrared (ftir) difference spectroscopy in ps ii core complexes of synechocystis sp. pcc 6803 using the experimental conditions previously optimized to generate the pure tyrd./tyrd ftir difference spectrum in ps ii-enriched membranes of spinach [hienerwadel, r., boussac, a., breton, j., and berthomieu, c. (1996) biochemistry 35, 115447-115460]. ir modes of tyrd and tyrd. ... | 1997 | 9398191 |
| photoinactivation of the f1-atpase from spinach chloroplasts by dequalinium is accompanied by derivatization of methionine beta183. | in contrast to the f1-atpases from bovine mitochondria and the thermophilic bacillus ps3, which are reversibly inhibited by dequalinium in the absence of irradiation, the mg2+-atpase activity of heat- or dithiothreitol-activated chloroplast f1 (cf1) from spinach chloroplasts is slightly stimulated by dequalinium. conversely, dequalinium is a partial inhibitor (maximal inhibition is 85-90%) of the ca2+-atpase of cf1 activated by heat, dithiothreitol, or octylglucoside. the mg2+- and ca2+-atpase a ... | 1997 | 9405435 |
| expression of the spinach betaine aldehyde dehydrogenase (badh) gene in transgenic tobacco plants. | plasmid pls9 contains a 1.5-kb of spinach cdna including its complete open reading frame. the 1.5-kb badh cdna was cut from pls9 using restriction enzyme and was inserted into the expression cassette of plasmid pyh between the camv 35s promoter and polya signal sequence. the 35s-badh cdna-polya fragment of pyh was cloned into a polylinker cloning site of the binary vector pbin19. the resulting plasmid pbinbadh-s was transferred to agrobacterium tumefacies lba4404. the tobacco plants were transfo ... | 1997 | 9429776 |
| the involvement of the two acidic patches of spinach plastocyanin in the reaction with photosystem i. | six different spinach plastocyanin mutants have been constructed by site-directed mutagenesis and expressed in escherichia coli to probe the importance of the two acidic patches in the interaction with photosystem i. the mutants were: asp42lys, glu43asn, glu43lys, glu43gln/asp44asn, glu59lys/glu60gln and glu43asn/glu59lys/glu60gln and they have been characterised by optical absorption and epr spectroscopy, redox titrations and isoelectric focusing. the electron transfer to photosystem i was inve ... | 1997 | 9452765 |
| vascular movement of beet necrotic yellow vein virus in beta macrocarpa is probably dependent on an rna 3 sequence domain rather than a gene product. | rnas 1 and 2 of beet necrotic yellow vein virus (bnyvv) carry the functions enabling viral rna replication, cell-to-cell movement, virus assembly and vascular movement of the virus in the systemic host spinacea oleracea. in beta macrocarpa, on the other hand, bnyvv rna 3 is required for vascular movement. replication-competent rna 3 transcripts carrying various point mutations and deletions were coinnoculated with rnas 1 and 2 to young leaves of b. macrocarpa and the ability of the virus to mult ... | 1998 | 9472625 |
| immunization against rabies with plant-derived antigen. | we previously demonstrated that recombinant plant virus particles containing a chimeric peptide representing two rabies virus epitopes stimulate virus neutralizing antibody synthesis in immunized mice. we show here that mice immunized intraperitoneally or orally (by gastric intubation or by feeding on virus-infected spinach leaves) with engineered plant virus particles containing rabies antigen mount a local and systemic immune response. after the third dose of antigen, given intraperitoneally, ... | 1998 | 9482911 |
| a matrix-located processing peptidase of plant mitochondria. | nuclear-encoded mitochondrial precursor proteins are proteolytically processed inside the mitochondrion after import. the general mitochondrial processing activity in plant mitochondria has been shown to be integrated into the cytochrome bc1 complex of the respiratory chain. here we investigate the occurrence of an additional, matrix-located processing activity by incubation of the precursors of the soybean mitochondrial proteins, alternative oxidase, the fad subunit of the atp synthetase and th ... | 1998 | 9484472 |
| the role of aromatic and acidic amino acids in the electron transfer reaction catalyzed by spinach ferredoxin-dependent glutamate synthase. | treatment of the ferredoxin-dependent, spinach glutamate synthase with n-bromosuccinimide (nbs) modifies 2 mol of tryptophan residues per mol of enzyme, without detectable modification of other amino acids, and inhibits enzyme activity by 85% with either reduced ferredoxin or reduced methyl viologen serving as the source of electrons. the inhibition of ferredoxin-dependent activity resulting from nbs treatment arises entirely from a decrease in the turnover number. complex formation of glutamate ... | 1998 | 9507092 |
| molecular characterization and physiological role of a glyoxysome-bound ascorbate peroxidase from spinach. | cdnas encoding two cytosolic and two chloroplastic ascorbate peroxidase (asap) isozymes from spinach have been cloned recently [ishikawa et al. (1995) febs lett. 367: 28, (1996) febs lett. 384: 289]. we herein report the cloning of the fifth cdna of an asap isozyme which localizes in spinach glyoxysomes (gasap). the open reading frame of the 858-base pair cdna encoded 286 amino acid residues with a calculated molecular mass of 31,507 da. by determination of the latency of asap activity in intact ... | 1998 | 9516999 |
| purification, properties and in situ localization of the amphibolic enzymes d-ribulose 5-phosphate 3-epimerase and transketolase from spinach chloroplasts. | the amphibolic enzymes d-ribulose 5-phosphate 3-epimerase and transketolase have been purified from stroma extracts of spinach chloroplasts using ammonium sulfate fractionation and fplc. for the native enzymes, a molecular mass of 180 kda for epimerase and 160 kda for transketolase was found and the molecular masses of the subunits was determined to be 23 kda for epimerase and 74 kda for transketolase. protein sequencing of the purified chloroplast enzymes revealed the nh2-terminal amino acid se ... | 1998 | 9523694 |
| fluorescence resonance energy transfer mapping of subunit delta in spinach chloroplast f1 atpase. | despite the considerable progress in the field of f0f1-atpases caused by solving the 2.8-a structure of mitochondrial f1 atpase [abrahams, j. p., leslie, a. g. w., lutter, r. & walker, j. e. (1994) nature 370, 621-628], little is known about the position and function of the enzyme's small subunits which were not resolved in the x-ray analysis. we have previously genetically engineered cys residues into the delta subunit of chloroplast f1 and used these mutant subunits in cross-linking studies [l ... | 1998 | 9523699 |
| characterization of a gene for spinach cap160 and expression of two spinach cold-acclimation proteins in tobacco. | the cdna sequence for cap160, an acidic protein previously linked with cold acclimation in spinach (spinacia oleracea l.), was characterized and found to encode a novel acidic protein of 780 amino acids having very limited homology to a pair of arabidopsis thaliana stress-regulated proteins, rd29a and rd29b. the lack of similarity in the structural organization of the spinach and arabidopsis genes highlights the absence of a high degree of conservation of this cold-stress gene across taxonomic b ... | 1998 | 9536054 |
| the 23 and 17 kda extrinsic proteins of photosystem ii modulate the magnetic properties of the s1-state manganese cluster. | an s1-state parallel polarization "multiline" epr signal arising from the oxygen-evolving complex has been detected in spinach (psii) membrane and core preparations depleted of the 23 and 17 kda extrinsic polypeptides, but retaining the 33 kda extrinsic protein. this s1-state multiline signal, with an effective g value of 12 and at least 18 hyperfine lines, has previously been detected only in psii preparations from the cyanobacterium sp. synechocystis sp. pcc6803 [campbell, k. a., peloquin, j. ... | 1998 | 9548734 |
| cdna sequence and heterologous expression of monomeric spinach pullulanase: multiple isomeric forms arise from the same polypeptide. | the spinach pullulanase gene was cloned and sequenced using peptide sequences of the purified enzyme as a starting point and employing pcr techniques and cdna library screening. its open reading frame codes for a protein of 964 amino acids which represents a precursor of the pullulanase. the n-terminal transit peptide consists of 65 amino acids, and the mature protein, comprising 899 amino acids, has a calculated molecular mass of 99kda. pullulanase is a member of the alpha-amylase family. in ad ... | 1998 | 9560325 |
| optimization of the cleavage reaction for cyanylated cysteinyl proteins for efficient and simplified mass mapping. | peptide chains can be cleaved selectively on the n-terminal side of cysteine residues after cyanylation of sulfhydryl groups to form an amino-terminal peptide and a series of 2-iminothiazolidine-4-carboxyl peptides. this paper describes a systematic study that was carried out to elucidate the effects of peptide structure and reaction conditions on the kinetics of the reactions and the yields of cleavage products. both cleavage and beta-elimination reactions under different conditions (ph 8.0, 9. ... | 1998 | 9570840 |
| analysis of the reaction coordinate of photosynthetic water oxidation by kinetic measurements of 355 nm absorption changes at different temperatures in photosystem ii preparations suspended in either h2o or d2o. | flash-induced absorption changes at 355 nm were measured at different temperatures within the range of 2 degrees c </= theta </= 25 degrees c in dark-adapted ps ii core complexes from spinach [o2 evolution rate: 1500 +/- 100 micromol of o2 (mg of chl)-1 h-1] that were dissolved either in h2o- or in d2o-containing buffer. comparative measurements were performed at 20 degrees c in h2o- or d2o-containing suspensions of ps ii membrane fragments [o2 evolution rate: 600 +/- 40 micromol of o2 (mg of ch ... | 1997 | 9220978 |
| comparative study on recombinant chloroplastic and cytosolic ascorbate peroxidase isozymes of spinach. | the spinach stromal, thylakoid-bound, and cytosolic ascorbate peroxidase isozymes (ec 1.11.1.11) were overexpressed in escherichia coli, and their enzymatic properties were compared with the respective native isozymes. the purification of the recombinant stromal and cytosolic ascorbate peroxidases using the conventional column chromatography yielded 0.73 and 2.2 mg of protein/liter of bacteria culture with enzyme activities of 800 and 486 micromol min-1 mg protein-1, respectively. in every respe ... | 1998 | 9578600 |
| characterization of protein-binding to the spinach chloroplast psba mrna 5' untranslated region. | rna-binding proteins play a major role in regulating mrna metabolism in chloroplasts. in this work we characterized two proteins, of 43 and 47 kda, which bind to the spinach psba mrna 5' untranslated region (psba encoding the d1 protein of photosystem ii). the 43 kda protein, which is present in the stroma and in membranes, co-sediments with a complex of 68s. it was purified, and the n-terminal sequence was determined. upon homology search it was identified as the chloroplast homologue of the es ... | 1998 | 9580673 |
| electron donation to the flavoprotein nifl, a redox-sensing transcriptional regulator. | transcriptional control of the nitrogen fixation (nif) genes in response to oxygen in azotobacter vinelandii is mediated by nitrogen fixation regulatory protein l (nifl), a regulatory flavoprotein that modulates the activity of the transcriptional activator nitrogen fixation regulatory protein a (nifa). cd spectra of purified nifl indicate that fad is bound to nifl in an asymmetric environment and the protein is predominantly alpha-helical. the redox potential of nifl is -226 mv at ph 8 as deter ... | 1998 | 9601070 |
| analysis of plastid dna-like sequences within the nuclear genomes of higher plants. | a wide-ranging examination of plastid (pt)dna sequence homologies within higher plant nuclear genomes (promiscuous dna) was undertaken. digestion with methylation-sensitive restriction enzymes and southern analysis was used to distinguish plastid and nuclear dna in order to assess the extent of variability of promiscuous sequences within and between plant species. some species, such as gossypium hirsutum (cotton), nicotiana tabacum (tobacco), and chenopodium quinoa, showed homogenity of these se ... | 1998 | 9615455 |
| molecular characterisation of the 76 kda iron-sulphur protein subunit of potato mitochondrial complex i. | genes encoding subunits of complex i (ec 1.6.5.3) of the mitochondrial respiratory chain vary in their locations between the mitochondrial and nuclear genomes in different organisms, whereas genes for a homologous multisubunit complex in chloroplasts have to date only been found on the plastid genome. in potato (solanum tuberosum l.), the gene coding for the mitochondrial 76 kda iron-sulphur protein is identified in the nuclear genome. the gene is transcribed into polyadenylated mrna which is mo ... | 1998 | 9615461 |
| 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 |