| oxygen radical absorbance capacity of the phenolic compounds in plant extracts fractionated by high-performance liquid chromatography. | the oxygen radical absorbance capacity (orac) assay has been used to quantify the antioxidative properties of phytonutrients in fruit and vegetable extracts. using aqueous methanol extracts of tea and spinach as a model systems, separation of the components in the extracts by hplc followed by semiautomatic orac analysis of the column fractions permitted the determination of peroxyl-radical-scavenging profiles, demonstrating the relative abilities of the individual extract components to scavenge ... | 2001 | 11399037 |
| soret-excited raman spectroscopy of the spinach cytochrome b6f complex. structures of the b- and c-type hemes, chlorophyll a, and beta-carotene. | soret-excited resonance raman (rr) spectra of the spinach cytochrome b6f complex (cyt b6f) are reported for the oxidized, native, ascorbate-reduced, and dithionite-reduced forms. using excitations at 441.6, 413.1, and 406.7 nm, rr contributions of chlorophyll a, beta-carotene, the c-type heme of cytochrome f, and the b-type hemes of cytochrome b6 of the b6f complex were identified and the data compared to those previously obtained for the rhodospirillum rubrum bc1 complex [le moigne, c., schoepp ... | 2001 | 11401579 |
| nitrite reductase gene enrichment improves assimilation of no(2) in arabidopsis. | transgenic plants of arabidopsis bearing the spinach (spinacia oleracea) nitrite reductase (nir, ec 1.7.7.1) gene that catalyzes the six-electron reduction of nitrite to ammonium in the second step of the nitrate assimilation pathway were produced by use of the cauliflower mosaic virus 35s promoter and nopaline synthase terminator. integration of the gene was confirmed by a genomic polymerase chain reaction (pcr) and southern-blot analysis; its expression by a reverse transcriptase-pcr and two-d ... | 2001 | 11402201 |
| marker free transgenic plants: engineering the chloroplast genome without the use of antibiotic selection. | chloroplast genetic engineering offers several advantages over nuclear transformation including high levels of gene expression and gene containment. however, a consequence of placing a transgene in the chloroplast genome is that the antibiotic resistance genes used as selectable markers are highly amplified. engineering genetically modified (gm) crops without the use of antibiotic resistance genes should eliminate the potential risk of their transfer to the environment or gut microbes. therefore ... | 2001 | 11405095 |
| comparative study of thermal degradation of iron-sulfur proteins in spinach chloroplasts and membranes of thermophilic cyanobacteria: mössbauer spectroscopy. | mössbauer spectra of chloroplasts isolated from spinach plants grown in a mineral medium enriched with 57fe and mössbauer spectra of native membranes of the thermophilic cyanobacterium synechococcus elongatus contain a broad asymmetric doublet typical of the iron-sulfur proteins of photosystem (ps) i. exposure of chloroplasts to temperatures of 20-70 degrees c significantly modifies the central part of the spectra. this spectral change is evidence of decreased magnitude of the quadrupole splitti ... | 2001 | 11405887 |
| isolation and characterization of structurally novel antimutagenic flavonoids from spinach (spinacia oleracea). | thirteen compounds, isolated from spinach (spinacia oleracea), acted as antimutagens against the dietary carcinogen 2-amino-3-methylimidazo[4,5-f]quinoline in salmonella typhimurium ta 98. the antimutagens were purified by preparative and micropreparative hplc from a methanol/water (70:30, v/v) extract of dry spinach (commercial product) after removal of lipophilic compounds such as chlorophylls and carotenoids by solid-phase extraction (spe). pure active compounds were identified by instrumenta ... | 2001 | 11409964 |
| role of the atp synthase alpha-subunit in conferring sensitivity to tentoxin. | tentoxin, produced by phytopathogenic fungi, selectively affects the function of the atp synthase enzymes of certain sensitive plant species. binding of tentoxin to a high affinity (k(i) approximately 10 nm) site on the chloroplast f(1) (cf(1)) strongly inhibits catalytic function, whereas binding to a second, lower affinity site (k(d) > 10 microm) leads to restoration and even stimulation of catalytic activity. sensitivity to tentoxin has been shown to be due, in part, to the nature of the amin ... | 2001 | 11412108 |
| serine acetyltransferase involved in cysteine biosynthesis from spinach: molecular cloning, characterization and expression analysis of cdna encoding a plastidic isoform. | a cdna clone that encodes a chloroplast-localizing isoform of serine acetyltransferase (satase) (ec 2.3.1.30) was isolated from spinach (spinacia oleracea l.). the cdna encodes a polypeptide of 347 amino acids containing a putative transit peptide of ca. 60-70 amino acids at the n-terminal. deduced amino acid sequence of satase from spinach exhibited homology with other satases from plants. dna blot hybridization analysis showed the presence of 2-3 copies of sat gene in the genome of spinach. rn ... | 2001 | 11427682 |
| cloning of dna encoding a catalytic subunit of snf1-related protein kinase-1 (snrk1-alpha1), and immunological analysis of multiple forms of the kinase, in spinach leaf. | using a pcr approach, we have cloned dna encoding a catalytic subunit isoform (snrk1-alpha1) of snf1-related protein kinase-1 from spinach leaf. the predicted amino acid sequence falls into the snrk1a sub-family, and is closely related to snrk1a sequences expressed in cucumber, arabidopsis thaliana, tobacco and potato. we have generated two affinity-purified antipeptide antibodies (anti-rass and anti-aef) based on the predicted amino acid sequence of spinach snrk1-alpha1. they were used to analy ... | 2001 | 11430435 |
| antibodies to assess phosphorylation of spinach leaf nitrate reductase on serine 543 and its binding to 14-3-3 proteins. | to monitor site-specific phosphorylation of spinach leaf nitrate reductase (nr) and binding of the enzyme to 14-3-3 proteins, serum antibodies were raised that select for either serine 543 phospho- or dephospho-nr. the dephospho-specific antibodies blocked nr phosphorylation on serine 543. the phospho-specific antibodies prevented nr binding to 14-3-3s, nr inhibition by 14-3-3s, nr dephosphorylation on serine 543, and did not precipitate 14-3-3s together with nr. together, this confirms that 14- ... | 2001 | 11432934 |
| electrogenic reduction of the primary electron donor p700 by plastocyanin in photosystem i complexes. | an electrometric technique was used to investigate electron transfer between spinach plastocyanin (pc) and photooxidized primary electron donor p700 in photosystem i (ps i) complexes from the cyanobacterium synechocystis sp. pcc 6803. in the presence of pc, the fast unresolvable kinetic phase of membrane potential generation related to electron transfer between p700 and the terminal iron-sulfur acceptor f(b) was followed by additional electrogenic phases in the microsecond and millisecond time s ... | 2001 | 11445080 |
| plants synthesize ethanolamine by direct decarboxylation of serine using a pyridoxal phosphate enzyme. | the established pathways from serine to ethanolamine are indirect and involve decarboxylation of phosphatidylserine. here we show that plants can decarboxylate serine directly. using a radioassay based on ethanolamine (etn) formation, pyridoxal 5'-phosphate-dependent l-serine decarboxylase (sdc) activity was readily detected in soluble extracts from leaves of diverse species, including spinach, arabidopsis, and rapeseed. a putative arabidopsis sdc cdna was identified by searching genbank for seq ... | 2001 | 11461929 |
| polynucleotide phosphorylase functions as both an exonuclease and a poly(a) polymerase in spinach chloroplasts. | the molecular mechanism of mrna degradation in the chloroplast consists of sequential events including endonucleolytic cleavage, the addition of poly(a)-rich sequences to the endonucleolytic cleavage products, and exonucleolytic degradation by polynucleotide phosphorylase (pnpase). in escherichia coli, polyadenylation is performed mainly by poly(a)-polymerase (pap) i or by pnpase in its absence. while trying to purify the chloroplast pap by following in vitro polyadenylation activity, it was fou ... | 2001 | 11463823 |
| a calcium-binding protein with similarity to serum albumin localized to the er-golgi network and cell walls of spinach (spinacia oleracea). | using polyclonal antibodies raised against human serum albumin (hsa), a 70-kda microsomal protein with an isoelectric point of approximately 6.5 was detected in spinach (spinacia oleracea l.). the protein was purified by selective ammonium sulfate precipitation and anion exchange hplc. the protein shared 100% identity with the first 15 amino acids at the nh2 terminus of hsa, including the x-x-h amino acid region, which was identified in hsa as being responsible for binding of copper, zinc, indol ... | 2001 | 11473705 |
| occurrence of campylobacter jejuni in vegetables. | in order to understand the importance of vegetables in the transmission of thermophilic campylobacter, 56 samples of different vegetables were screened. out of these, 2 samples (1 spinach and 1 fenugreek) revealed the presence of campylobacter jejuni biotype i. both the isolates were enteropathogenic in rat ileal loop test. | 2001 | 11482564 |
| ferredoxin:nadp+ oxidoreductase is a subunit of the chloroplast cytochrome b6f complex. | purified detergent-soluble cytochrome b6f complex from chloroplast thylakoid membranes (spinach) and cyanobacteria (mastigocladus laminosus) was highly active, transferring 300-350 electrons per cyt f/s. visible absorbance spectra showed a red shift of the cytochrome f alpha-band and the qy chlorophyll a band in the cyanobacterial complex and an absorbance band in the flavin 450-480-nm region of the chloroplast complex. an additional high molecular weight (m(r) approximately 35,000) polypeptide ... | 2001 | 11483610 |
| dissipation of epoxiconazole in the paddy field under subtropical conditions of taiwan. | the environmental fate and distribution of fungicide epoxiconazole were studied by a rice paddy field model ecosystem. one week before the head-sprouting stage, rice plant was treated separately once with opus (tradename of epoxiconazole) 12% sc 2.1 kg ha(-1) and 1.4 kg ha(-1), respectively. soil, water and rice plant were sampled seven days intervals nine times after application. the bioconcentration factor of epoxiconazole on mosquito fish in the ecosystem was also determined, based on the amo ... | 2001 | 11495019 |
| the effect of natural antioxidants, nao and apocynin, on oxidative stress in the rat heart following lps challenge. | oxidative damage plays a key role in septic shock induced by lipopolysaccharide (lps) which is known to enhance the formation of reactive oxygen species (ros). in this study, biochemical parameters indicative of oxidative stress were tested in the rat heart following lps challenge, with and without pretreatment with the antioxidants nao (natural antioxidant) and apocynin. nao is a natural antioxidant isolated and purified from spinach and its main components are flavonoids and coumaric acid deri ... | 2001 | 11514100 |
| effects of water-soluble antioxidant from spinach, nao, on doxorubicin-induced heart injury. | doxorubicin (dox) produces clinically restorative responses in numerous human cancers, but its cardiotoxicity has limited its usefulness. because reactive oxygen species may affect dox-induced antitumor activity and cardiotoxicity, we evaluated the prophylactic effect of spinach natural antioxidant (nao) on dox-induced cardiotoxicity and oxidative stress in female balb/c mice using histological, electron microscopical and biochemical parameters. mice were treated with nao for 7 days prior to and ... | 2001 | 11530832 |
| subunit positioning and transmembrane helix organisation in the core dimer of photosystem ii. | recently 3d structural models of the photosystem ii (psii) core dimer complexes of higher plants (spinach) and cyanobacteria (synechococcus elongatus) have been derived by electron [rhee et al. (1998) nature 396, 283-286; hankamer et al. (2001) j. struct. biol., in press] and x-ray [zouni et al. (2001) nature 409, 739-743] crystallography respectively. the intermediate resolutions of these structures do not allow direct identification of side chains and therefore many of the individual subunits ... | 2001 | 11532446 |
| atp synthase: constrained stoichiometry of the transmembrane rotor. | recent structural data suggest that the number of identical subunits (c or iii) assembled into the cation-powered rotor of f1f0 atp synthase depends on the biological origin. atomic force microscopy allowed individual subunits of the cylindrical transmembrane rotors from spinach chloroplast and from ilyobacter tartaricus atp synthase to be directly visualized in their native-like environment. occasionally, individual rotors exhibit structural gaps of the size of one or more subunits. complete ro ... | 2001 | 11532457 |
| heterologous, splicing-dependent rna editing in chloroplasts: allotetraploidy provides trans-factors. | rna editing is unique among post-transcriptional processes in plastids, as it exhibits extraordinary phylogenetic dynamics leading to species-specific editing site patterns. the evolutionary loss of a site is considered to entail the loss of the corresponding nuclear-encoded site-specific factor, which prevents the editing of foreign, i.e. heterologous, sites. we investigated the editing of short 'spliced' and 'unspliced' ndha gene fragments from spinach in nicotiana tabacum (tobacco) in vivo us ... | 2001 | 11532951 |
| effects of sequential deletions of residues from the n- or c-terminus on the functions of epsilon subunit of the chloroplast atp synthase. | ten truncated mutants of chloroplast atp synthase epsilon subunit from spinach (spinacia oleracea), which had sequentially lost 1-5 amino acid residues from the n-terminus and 6-10 residues from the c-terminus, were generated by pcr. these mutants were overexpressed in escherichia coli, reconstituted with soluble and membrane-bound cf(1), and the atpase activity and proton conductance of thylakoid membrane were examined. deletions of as few as 3 amino acid residues from the n-terminus or 6 resid ... | 2001 | 11535058 |
| potential utilization of algal protein concentrate as a food ingredient in space habitats. | green alga scenedesmus obliquus was studied as one of the potential sources of macronutrients in a space habitat. algal protein concentrate (70.5% protein) was incorporated into a variety of food products such as bran muffins, fettuccine (spinach noodle imitation) and chocolate chip cookies. food products containing 20 to 40% of incorporated algal proteins were considered. in the sensory analysis the greenish color of the bran muffins and cookies was not found to be objectional. the mild spin ... | 1989 | 11538068 |
| identification of an nadp/thioredoxin system in chlamydomonas reinhardtii. | the protein components of the nadp/thioredoxin system, nadp-thioredoxin reductase (ntr) and thioredoxin h, have been purified and characterized from the green alga, chlamydomonas reinhardtii. the analysis of this system confirms that photoautotrophic chlamydomonas cells resemble leaves in having both an nadp- and ferrodoxin-linked thioredoxin redox system. chlamydomonas thioredoxin h, which is smaller on sodium dodecyl sulfate-polyacrylamide gel electrophoresis than thioredoxin m from the same ... | 1991 | 11538123 |
| ion-exchange chromatography separates activities synthesizing and degrading fructose 2,6-bisphosphate from c3 and c4 leaves but not from rat liver. | fructose-6-phosphate,2-kinase and fructose-2,6-bisphosphatase were separated on the basis of charge from leaves of c3 (spinach, lettuce, and pea) and c4 (sorghum and amaranthus) plants but not from rat liver--a tissue known to contain a bifunctional enzyme with both activities. [2-32p]fructose 2,6-bisphosphate binding experiments also suggest that the major forms of these activities reside on different proteins in leaves. | 1987 | 11539704 |
| recycling of na in advanced life support: strategies based on crop production systems. | sodium is an essential dietary requirement in human nutrition, but seldom holds much importance as a nutritional element for crop plants. in advanced life support (als) systems, recycling of gases, nutrients, and water loops is required to improve system closure. if plants are to play a significant role in recycling of human wastes, na will need to accumulate in edible tissues for return to the crew diet. if crops fail to accumulate the incoming na into edible tissues, na could become a threat t ... | 1999 | 11542242 |
| the superiority of organically cultivated vegetables to general ones regarding antimutagenic activities. | we found organically cultivated (oc) vegetables, using a water-soluble chitosan as a soil improvement agent and leaf surface spray, had much longer shelf life and better taste than that of generally cultivated (gc) vegetables. the purpose of this study is to determine the relative antimutagenic activity between oc and gc vegetables. eleven oc vegetables were harvested in march and april in 1999 and 2000, and gc ones were supplied as a control from nearby farms on the same date. the former vegeta ... | 2001 | 11551483 |
| a role for rubredoxin in oxidative stress protection in desulfovibrio vulgaris: catalytic electron transfer to rubrerythrin and two-iron superoxide reductase. | desulfovibrio vulgaris rubredoxin, which contains a single [fe(scys)4] site, is shown to be a catalytically competent electron donor to two enzymes from the same organism, namely, rubrerythrin and two-iron superoxide reductase (a.k.a. rubredoxin oxidoreductase or desulfoferrodoxin). these two enzymes have been implicated in catalytic reduction of hydrogen peroxide and superoxide, respectively, during periods of oxidative stress in d. vulgaris, but their proximal electron donors had not been char ... | 2001 | 11566030 |
| the third naturally occurring attractant toward zoospores of phytopathogenic aphanomyces cochlioides from the spinacia oleracea host plant. | a bioassay-guided survey of spinach leaf constituents resulted in 5,4'-dihydroxy-3,3'-dimethoxy-6,7-methylenedioxyflavone being identified as the third naturally-occurring attractant in the host plant toward the zoospores of its pathogen, aphanomyces cochlioides. the isolate showed attracting activity around chromosorb w aw particles (60-80 mesh) coated with a 10(-5) m solution in a zoospore suspension. however, this activity was 1/100-1/1000 less than that of cochliophilin a, an attractant in t ... | 2001 | 11577714 |
| electron transport inhibitor in cyperus javanicus. | the natural quinone, hydroxydietrichequinone (3-heptadec-8-enyl-2-hydroxy-5-methoxy-[1,4]benzoquinone) is a secondary metabolite of cyperus javanicus. we found that this quinone inhibited both mitochondrial respiration and photosynthesis in their electron transportation systems. the quinone was found to have a mode of action against the ubiquinone reductase site from the results of different electron donor experiments on intact mitochondria from rat liver. the electron transport system, photosys ... | 2001 | 11577726 |
| determination of folates in foods by high-performance liquid chromatography with fluorescence detection after precolumn conversion to 5-methyltetrahydrofolates. | a liquid chromatographic-fluorimetric determination of folates in foodstuffs including their extraction, without or with deconjugation, chemical conversion to 5-ch3-h4pteglu(n) and purification of the extract by affinity chromatography is reported. the conversion enables the analysis of total folates and also of the contents of the different mono- and polyglutamate forms of the folates. the method has a satisfactory day-to-day repeatability (never,more than 10%) and a very low detection limit (0 ... | 2001 | 11589473 |
| substrate water exchange in photosystem ii depends on the peripheral proteins. | the (18)o exchange rates for the substrate water bound in the s(3) state were determined in different photosystem ii sample types using time-resolved mass spectrometry. the samples included thylakoid membranes, salt-washed triton x-100-prepared membrane fragments, and purified core complexes from spinach and cyanobacteria. for each sample type, two kinetically distinct isotopic exchange rates could be resolved, indicating that the biphasic exchange behavior for the substrate water is inherent to ... | 2001 | 11595731 |
| implications of secondary structure prediction and amino acid sequence comparison of class i and class ii phosphoribosyl diphosphate synthases on catalysis, regulation, and quaternary structure. | spinach 5-phospho-d-ribosyl alpha-1-diphosphate (prpp) synthase isozyme 4 was synthesized in escherichia coli and purified to near homogeneity. the activity of the enzyme is independent of p(i); it is inhibited by adp in a competitive manner, indicating a lack of an allosteric site; and it accepts atp, datp, gtp, ctp, and utp as diphosphoryl donors. all of these properties are characteristic for class ii prpp synthases. k(m) values for atp and ribose 5-phosphate are 77 and 48 microm, respectivel ... | 2001 | 11604537 |
| voltammetry of plastocyanin at a graphite electrode: effects of structure, charge, and electrolyte. | comparative voltammetric studies on anabaena variabilis plastocyanin (positively charged at neutral ph) and spinach and poplar plastocyanins (negatively charged at neutral ph) have been undertaken at an edge-plane graphite electrode as a function of ionic strength, ph, and mg(2+) concentration at 3 degrees c. the aim was to provide a more detailed understanding of the influence of the electrode-protein (solution) interfacial characteristics, as well as the variation of the formal potential with ... | 1996 | 11666900 |
| the assembly of the psad subunit into the membranal photosystem i complex occurs via an exchange mechanism. | psad is a peripheral stromal-facing subunit of photosystem i (psi), a multisubunit complex of the thylakoid membranes. psad plays a major role in both the function and assembly of psi. past studies with radiolabeled psad indicated that psad is able to assemble in vitro specifically into the psi complex. to unravel the mechanism by which this assembly takes place, the following steps were taken. (i) mature psad of spinach and psad of the prokaryotic caynobacterium mastigocladus laminosus, both be ... | 2001 | 11669611 |
| formation, properties, and characterization of a fully reduced fe(ii)fe(ii) form of spinach (and parsley) [2fe-2s] ferredoxin with the macrocyclic complex [cr(15-anen(4))(h(2)o)(2)](2+) as reductant. | reduction of spinach and parsley ferredoxin fdi in the fe(iii)fe(iii) state with the 1,4,8,12-tetraazacyclopentadecane complex [cr(15-anen(4))(h(2)o)(2)](2+), here written as cr(ii)l, provides the first evidence for two 1-equiv steps yielding an fe(ii)fe(ii) product. rate constants (25 degrees c) for spinach fdi are 2760 and 660 m(-)(1) s(-)(1), respectively, at ph 7.5, i = 0.100 m (nacl). an important observation is that the cr(iii)l generated in the first step remains attached to the fe(ii)fe( ... | 1997 | 11669717 |
| phytotoxic naphthopyranone derivatives from the coprophilous fungus guanomyces polythrix. | reinvestigation of the fermentation broth and mycelium of the coprophilous fungus guanomyces polythrix, grown in static conditions, led to the isolation of several phytotoxic compounds, including two new naphthopyranone derivatives, namely (2s, 3r)-5-hydroxy-6,8-dimethoxy-2,3-dimethyl-2,3-dihydro-4h-naphtho[2,3-b]-pyran-4-one and (2s, 3r)-5-hydroxy-6,8,10-trimethoxy-2,3-dimethyl-2,3-dihydro-4h-naphtho[2,3-b]-pyran-4-one. the structures of the new compounds were established by spectral and chirop ... | 2001 | 11672740 |
| crystallization and preliminary x-ray diffraction analysis of glutathione-dependent dehydroascorbate reductase from spinach chloroplasts. | glutathione-dependent dehydroascorbate reductase (gsh-dhar) catalyzes the reduction of dehydroascorbate to ascorbate using reduced glutathione as the electron donor. gsh-dhar from spinach chloroplasts produced in escherichia coli was crystallized by the hanging-drop vapour-diffusion method. the crystals were monoclinic, space group c2, with unit-cell parameters a = 98.25, b = 39.96, c = 106.86 a, beta = 110.46 degrees. the asymmetric unit contained two molecules, giving a crystal volume per enzy ... | 2001 | 11679758 |
| carotenoids affect proliferation of human prostate cancer cells. | we investigated whether various carotenoids present in foodstuffs were potentially involved in cancer-preventing action on human prostate cancer. the effects of 15 kinds of carotenoids on the viability of three lines of human prostate cancer cells, pc-3, du 145 and lncap, were evaluated. when the prostate cancer cells were cultured in a carotenoid-supplemented medium for 72 h at 20 micromol/l, 5,6-monoepoxy carotenoids, namely, neoxanthin from spinach and fucoxanthin from brown algae, significan ... | 2001 | 11739884 |
| rubiscolin, a delta selective opioid peptide derived from plant rubisco. | we found that the sequences ypldl and ypldlf in the large subunit of spinach d-ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) met the structure yp-aliphatic amino acid which might have opioid activity. we then synthesized these peptides to test their opioid activity. the ic(50) of these peptides in mouse vas deferens assay were 51.0 microm and 24.4 microm, respectively, and those in delta receptor binding assay using [(3)h]deltorphin ii as radioligand were 2.09 microm and 0.93 microm, ... | 2001 | 11741591 |
| thioredoxin-mediated reductive activation of a protein kinase for the regulatory phosphorylation of c4-form phosphoenolpyruvate carboxylase from maize. | the activity of phosphoenolpyruvate carboxylase (pepc, ec4.1.1.31) for the c4 photosynthesis is known to be regulated mainly in response to light/dark transitions through reversible phosphorylation by a specific protein kinase (pk). pepc-pk with an m(r) of 30 kda was purified about 1.4 million-fold to homogeneity from maize leaves and characterized. the purified pepc-pk was readily inactivated under mild oxidative conditions, but the activity could be recovered by dithiothreitol (dtt). the recov ... | 2001 | 11773521 |
| the plant s-adenosyl-l-methionine:mg-protoporphyrin ix methyltransferase is located in both envelope and thylakoid chloroplast membranes. | chlorophyll biosynthesis requires a metabolic dialog between the chloroplast envelope and thylakoids where biosynthetic activities are localized. here, we report the first plant s-adenosyl-l-methionine:mg-protoporphyrin ix methyltransferase (mgp(ix)mt) sequence identified in the arabidopsis genome owing to its similarity with the synechocystis sp. mgp(ix)mt gene. after expression in escherichia coli, the recombinant arabidopsis thaliana cdna was shown to encode a protein having mgp(ix)mt activit ... | 2002 | 11784318 |
| a functional role for tyrosine-d in assembly of the inorganic core of the water oxidase complex of photosystem ii and the kinetics of water oxidation. | the role of d2-tyr160 (y(d)), a photooxidizable residue in the d2 reaction center polypeptide of photosystem ii (psii), was investigated in both wild type and a mutant strain (d2-tyr160phe) in which phenylalanine replaces y(d) in the cyanobacterium synechocystis sp. (strain pcc 6803). y(d) is the symmetry-related tyrosine that is homologous to the essential photoactive tyr161(y(z)) of the d1 polypeptide of psii. we compared the flash-induced yield of o(2) in intact, functional psii centers from ... | 2002 | 11790121 |
| decreased absorption and retention rates of magnesium in the rats fed on spinach-supplemented diets: possible explanations. | we studied the bioavailability of magnesium (mg) in spinach after boiling with distilled water, using mg-deficient growing male rats. the rats were fed a semipurified diet (mg:0.063 per cent (w/w)) for 3 days. then a mg-deficient diet (mg:0.001 per cent (w/w)) for 5 days. they were then divided randomly into 7 groups of 6 rats each, and fed the semipurified diet (mg: 0.063, 0.045 or 0.027 per cent (w/w)), or the spinach-supplemented diet (10 per cent (w/w) dried and powdered spinach after boilin ... | 2001 | 11794632 |
| cloning of the o-acetylserine lyase gene from the ruminal bacterium selenomonas ruminantium hd4. | the gene coding for o-acetylserine lyase (oasl) was cloned from a selenomonas ruminantium hd4 lambda zap ii genomic library by degenerative probe hybridization and complementation. sequence analysis revealed a 933 bp orf with a g + c content of 53%. the orf had significant homology with enzymes involved in cysteine biosynthesis. a curablastn homology search showed that the orf shared 59% nucleotide identity with the cysk of bacillus subtilis. the deduced amino acid sequence exhibited high (>70%) ... | 2002 | 11821922 |
| magneto-optical measurements of the pigments in fully active photosystem ii core complexes from plants. | preparation of a minimum psii core complex from spinach is described, containing four mn per reaction center (rc) and exhibiting high o2 evolving activity [approximately 4000 micromol of o2 (mg of chl)(-1) x h(-1)]. the complex consists of the cp47 and cp43 chlorophyll binding proteins, the rc d1/d2 pair, the cytochrome b559 subunits, and the mn-stabilizing psbo (33 kda) protein, all present in the same stoichiometric amounts found in the parent psii membranes. several small subunits are also pr ... | 2002 | 11827545 |
| the role of glycine betaine in the protection of plants from stress: clues from transgenic plants. | the acclimation of a plant to a constantly changing environment involves the accumulation of certain organic compounds of low molecular mass, known collectively as compatible solutes, in the cytoplasm. the evidence from numerous investigations of the physiology, genetics, biophysics and biochemistry of plants strongly suggests that glycine betaine (gb), an amphoteric quaternary amine, plays an important role as a compatible solute in plants under various types of environmental stress, such as hi ... | 2002 | 11841661 |
| small changes in the activity of chloroplastic nadp(+)-dependent ferredoxin oxidoreductase lead to impaired plant growth and restrict photosynthetic activity of transgenic tobacco plants. | a ferredoxin-nadp+ oxidoreductase (fnr) cdna from tobacco (nicotiana tabacum cv. samsun) was cloned and sequenced. comparison of the deduced amino acid sequence revealed high identity to fnr proteins from capsicum annuum, pisum sativum, spinacia oleracea and vicia faba. transgenic tobacco plants were generated that constitutively express the fnr cdna in reverse orientation between the camv 35s promoter and the polyadenylation signal of the octopine synthase gene. plants expressing the fnr antise ... | 2002 | 11844106 |
| crystal structure of the non-regulatory a(4 )isoform of spinach chloroplast glyceraldehyde-3-phosphate dehydrogenase complexed with nadp. | here, we report the first crystal structure of a photosynthetic glyceraldehyde-3-phosphate dehydrogenase (gapdh) complexed with nadp. the enzyme, purified from spinach chloroplasts, is constituted of a single type of subunit (a) arranged in homotetramers. it shows non-regulated nadp-dependent and nad-dependent activities, with a preference for nadp. the structure has been solved to 3.0 a resolution by molecular replacement. the crystals belong to space group c222 with three monomers in the asymm ... | 2001 | 11846565 |
| modulation of cyanoalanine synthase and o-acetylserine (thiol) lyases a and b activity by beta-substituted alanyl and anion inhibitors. | the reaction mechanisms of three enzymes belonging to a single gene family are compared: a cyanoalanine synthase and two isoforms of o-acetylserine (thiol) lyase (o-astl) isolated from spinach (spinacea oleracea l. cv. medina). o-astl represents a major regulatory point in the s-assimilatory pathway, and the related cyanoalanine synthase, which is specific to the mitochondrial compartment, has evolved an independent function of cyanide detoxification. all three enzymes catalysed both the cystein ... | 2002 | 11847242 |
| kinetic properties of bifunctional 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase from spinach leaves. | a cdna encoding 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase was isolated from a spinacia oleracea leaf library and used to express a recombinant enzyme in escherichia coli and spodoptera frugiperda cells. the insoluble protein expressed in e. coli was purified and used to raise antibodies. western blot analysis of a protein extract from spinach leaf showed a single band of 90.8 kda. soluble protein was purified to homogeneity from s. frugiperda cells infected with recombinant baculoviru ... | 2002 | 11856361 |
| identification of aminoethylcysteine ketimine decarboxylated dimer, a natural antioxidant, in dietary vegetables. | aminoethylcysteine ketimine decarboxylated dimer (simply named dimer) is a natural sulfur-containing tricyclic compound detected, until now, in human urine, bovine cerebellum, and human plasma. recently, the antioxidant properties of this compound have been demonstrated. in this investigation, the presence of aminoethylcysteine ketimine decarboxylated dimer was identified in garlic, spinach, tomato, asparagus, aubergine, onion, pepper, and courgette. identification of this compound in dietary ve ... | 2002 | 11902974 |
| structure of spinach chloroplast f1-atpase complexed with the phytopathogenic inhibitor tentoxin. | tentoxin, a natural cyclic tetrapeptide produced by phytopathogenic fungi from the alternaria species affects the catalytic function of the chloroplast f(1)-atpase in certain sensitive species of plants. in this study, we show that the uncompetitive inhibitor tentoxin binds to the alphabeta-interface of the chloroplast f(1)-atpase in a cleft localized at betaasp-83. most of the binding site is located on the noncatalytic alpha-subunit. the crystal structure of the tentoxin-inhibited cf(1)-comple ... | 2002 | 11904410 |
| molecular characterization of nucleus-localized rna-binding proteins from higher plants. | we report the isolation and characterization of genes from the higher plants arabidopsis, spinach and tobacco which code for nucleus-localized rna-binding proteins. common features of these polypeptides are glycine/arginine-rich regions with several rgg repeats at their n- and c-termini, which are sufficient for rna binding in northwestern assays. all polypeptides analysed contain two basic bipartite nuclear localization signals and translational fusions harbouring these regions with the beta-gl ... | 2002 | 11905967 |
| interaction of cytosolic and plastidic nitrogen metabolism in plants. | in angiosperms, the assimilation of ammonia resulting from nitrate reduction and from photorespiration depends on the operation of the plastidic gs/gogat cycle. the precursor for ammonia assimilation, 2-oxoglutarate, is synthesized in the mitochondria and in the cytosol. it is imported into the plastid by a 2-oxoglutarate/malate translocator (dit1). in turn, the product of ammonia assimilation, glutamate, is exported from the plastids by a glutamate/malate translocator (dit2). these transport pr ... | 2002 | 11912229 |
| assembly of photosystem i. i. inactivation of the ruba gene encoding a membrane-associated rubredoxin in the cyanobacterium synechococcus sp. pcc 7002 causes a loss of photosystem i activity. | a 4.4-kb hindiii fragment, encoding an unusual rubredoxin (denoted ruba), a homolog of the synechocystis sp. pcc 6803 gene slr2034 and arabidopsis thaliana hcf136, and the psbeflj operon, was cloned from the cyanobacterium synechococcus sp. pcc 7002. inactivation of the slr2034 homolog produced a mutant with no detectable phenotype and wild-type photosystem (ps) ii levels. inactivation of the ruba gene of synechococcus sp. pcc 7002 produced a mutant unable to grow photoautotrophically. ruba and ... | 2002 | 11914373 |
| the plant-specific function of 2-cys peroxiredoxin-mediated detoxification of peroxides in the redox-hierarchy of photosynthetic electron flux. | the 2-cysteine peroxiredoxins (2-cys prx) constitute an ancient family of peroxide detoxifying enzymes and have acquired a plant-specific function in the oxygenic environment of the chloroplast. immunocytochemical analysis and work with isolated intact chloroplasts revealed a reversible binding of the oligomeric form of 2-cys prx to the thylakoid membrane. the oligomeric form of the enzyme was enhanced under stress. the 2-cys prx has a broad substrate specificity with activity toward hydrogen pe ... | 2002 | 11929977 |
| microcosm wetlands for wastewater treatment with different hydraulic loading rates and macrophytes. | constructed wetlands (cw) usually require large land areas for treating wastewater. this study evaluated the feasibility of applying cw with less land requirement by operating a group of microcosm wetlands at a hydraulic retention time (hrt) of less than 4 d in southern taiwan. an artificial wastewater, simulating municipal wastewater containing 200 mg l(-1) of chemical oxygen demand (cod), 20 mg l(-1) of nh4+-n (an), and 20 mg l(-1) of po4(3-)-p (op), was the inflow source. three emergent plant ... | 2002 | 11931463 |
| electron crystallographic study of photosystem ii of the cyanobacterium synechococcus elongatus. | the determination of the structure of psii at high resolution is required in order to fully understand its reaction mechanisms. two-dimensional crystals of purified highly active synechococcus elongatus psii dimers were obtained by in vitro reconstitution. images of these crystals were recorded by electron cryo-microscopy, and their analysis revealed they belong to the two-sided plane group p22(1)2(1), with unit cell parameters a = 121 a, b = 333 a, and alpha = 90 degrees. from these crystals, a ... | 2002 | 11955064 |
| fruit polyphenolics and brain aging: nutritional interventions targeting age-related neuronal and behavioral deficits. | nutritional interventions, in this case, increasing dietary intake of fruits and vegetables, can retard and even reverse age-related declines in brain function and in cognitive and motor performance in rats. our lab has shown that as fischer 344 rats age their brains are increasingly vulnerable to oxidative stress. dietary supplementation with fruit or vegetable extracts high in antioxidants (e.g., blueberry, bb, spinach, respectively) can decrease this vulnerability to oxidative stress as asses ... | 2002 | 11976192 |
| comparison of the structure of the extrinsic 33 kda protein from different organisms. | the psbo gene encoding the extrinsic 33 kda protein of oxygen-evolving photosystem ii (psii) complex was cloned and sequenced from a red alga, cyanidium caldarium. the gene encodes a polypeptide of 333 residues, of which the first 76 residues served as transit peptides for transfer across the chloroplast envelope and thylakoid membrane. the mature protein consists of 257 amino acids with a calculated molecular mass of 28,290 da. the sequence homology of the mature 33 kda protein was 42.9-50.8% b ... | 2002 | 11978871 |
| light regulation of gibberellin biosynthesis and mode of action. | some phenotypic effects produced in plants by light are very similar to those induced by hormones. in this review, the light-gibberellin (ga) interaction in germination, de-etiolation, stem growth, and tuber formation (process regulated by gas) are discussed. germination of lettuce and arabidopsis seeds depends on red irradiation (r), which enhances the expression of ga 3-oxidase genes (ga3ox) and leads to an increase in active ga content. de-etiolation of pea seedling alters the expression of g ... | 2001 | 11986761 |
| the rate of charge recombination in photosystem ii. | loss by recombination of the charge separated state p(680+)q(a-) limits the performance of photosystem ii (ps ii) as a photochemical energy converter. time constants reported in literature for this process are mostly either near 0.17 ms or near 1.4 ms. the shorter time is found in plant ps ii when reduction of p(680+) by the secondary electron donor tyrosine z cannot occur because y(z) is already oxidized. the 1.4 ms recombination is seen in y(z)-less mutants of the cyanobacterium synechocystis. ... | 2002 | 11997139 |
| the antioxidant activity of regularly consumed fruit and vegetables reflects their phenolic and vitamin c composition. | recent studies are emphasising the importance and putative modes of action of specific flavonoids as bioactive components of the diet in in vivo and in vitro models. thus, it is important to have a clear idea of the major phenolic families of which fruit and vegetables are comprised and the levels contained therein. regularly consumed fruit and vegetables of mixed varieties available on the uk market were analysed for the composition of the major individual phenolic components. the total phenoli ... | 2002 | 11999391 |
| possible antitumor promoters in spinacia oleracea (spinach) and comparison of their contents among cultivars. | spinach leaves were found to contain two potent antitumor promoters as detected by the activity against tumor promoter-induced epstein-barr virus activation. the active components were identified as 1-o-alpha-linolenoyl-2-o-(7z,10z,13z)-hexadecatrienoyl-3-o-beta-d-galactopyranosyl-sn-glycerol and 1,2-di-o-alpha-linolenoyl-3-o-beta-d-galactopyranosyl-sn-glycerol by spectroscopic data and some chemical and enzymatic reactions. their contents significantly varied with the cultivar and with the cult ... | 2002 | 11999395 |
| molecular and biochemical characterization of a cold-regulated phosphoethanolamine n-methyltransferase from wheat. | a cdna that encodes a methyltransferase (mt) was cloned from a cold-acclimated wheat (triticum aestivum) cdna library. molecular analysis indicated that the enzyme wpeamt (wheat phosphoethanolamine [p-ea] mt) is a bipartite protein with two separate sets of s-adenosyl-l-met-binding domains, one close to the n-terminal end and the second close to the c-terminal end. the recombinant protein was found to catalyze the three sequential methylations of p-ea to form phosphocholine, a key precursor for ... | 2002 | 12011366 |
| action of an algicide from a cyanobacterium, oscillatoria laetevirens, on photosystem ii. | oscillatoria laetevirens produces an algicide, named oscillatorin (os), which inhibits growth of higher plants. effect of purified oscillatorin and some 'urea-triazine type' herbicides was studied on photosystem ii activity and composition of pigment protein complex in spinach thylakoid membrane. for oscillatorin the i50 at 10 microg chlorophyll concentration, inhibitor constant (ki), specific binding sites and hill coefficient were calculated to be 1.45, 0.15, 2.3 and 0.2 microm respectively. m ... | 2001 | 12018523 |
| increased tolerance to thermal inactivation of oxygen evolution in spinach photosystem ii membranes by substitution of the extrinsic 33-kda protein by its homologue from a thermophilic cyanobacterium. | photosynthetic oxygen evolution is an extremely heat-sensitive process and incubation of spinach photosystem ii (psii) membranes at 40 degrees c for only several minutes leads to its complete inactivation. substitution experiments of the spinach 33-kda manganese stabilizing protein by a homologue protein, isolated either from the thermophilic cyanobacterium phormidium laminosum, or from escherichia coli as a recombinant thermophilic cyanobacterial protein, showed a significant increase in tolera ... | 2002 | 12034468 |
| characterization of the oxygen tolerance of a hydrogenase linked to a carbon monoxide oxidation pathway in rubrivivax gelatinosus. | a hydrogenase linked to the carbon monoxide oxidation pathway in rubrivivax gelatinosus displays tolerance to o2. when either whole-cell or membrane-free partially purified hydrogenase was stirred in full air (21% o2, 79% n2), its h2 evolution activity exhibited a half-life of 20 or 6 h, respectively, as determined by an anaerobic assay using reduced methyl viologen. when the partially purified hydrogenase was stirred in an atmosphere containing either 3.3 or 13% o2 for 15 min and evaluated by a ... | 2002 | 12039713 |
| synthesis of a novel class of polyhydroxyalkanoates in arabidopsis peroxisomes, and their use in monitoring short-chain-length intermediates of beta-oxidation. | the poly[(r)-3-hydroxyalkanoate] (pha) synthase gene (phac(ac)) of aeromonas caviae fa440 was modified by adding a peroxisome targeting signal encoding the last 10 amino acids at the carboxyl-terminal of spinach glycolate oxidase. the modified gene was introduced into arabidopsis thaliana plants by agrobacterium-mediated transformation. the transgenic arabidopsis plant expressed the introduced gene and its protein, and it accumulated pha in its tissues. gas chromatography-mass spectrometry analy ... | 2002 | 12040103 |
| synthesis and bacterial expression of a gene encoding the heme domain of assimilatory nitrate reductase. | assimilatory nadh:nitrate reductase (ec 1.6.6.1), a complex mo-pterin-, cytochrome b(557)-, and fad-containing protein, catalyzes the regulated and rate-limiting step in the utilization of inorganic nitrogen by higher plants. a codon-optimized gene has been synthesized for expression of the central cytochrome b(557)-containing fragment, corresponding to residues a542-e658, of spinach assimilatory nitrate reductase. while expression of the full-length synthetic gene in escherichia coli did not re ... | 2002 | 12051681 |
| effects of food materials on removal of allium-specific volatile sulfur compounds. | effects of food materials were investigated on removal of several kinds of thiols, sulfides, and disulfides, which arise from vegetables of allium species during food preparation and eating. methanethiol, propanethiol, and 2-propenethiol were captured by raw foods such as fruits, vegetables, and mushrooms or a mixture of their acetone powders and phenolic compounds. the odor of diallyl disulfide was remarkably reduced by kiwi fruit, spinach, cutting lettuce, parsley, basil, mushrooms, and, parti ... | 2002 | 12059171 |
| the inhibition of ammonium uptake in excised birch (betula pendula) roots by batatasin-iii. | in northern sweden, plants growing in association with the clonal dwarf shrub empetrum hermaphroditum usually exhibit limited growth and are n-depleted. previous studies suggest that this negative effect by e. hermaphroditum may be explained, at least in part, by the release of phenolic compounds, particularly the dihydrostilbene, batatasin-iii from foliage to soil. in the present work, we investigated whether batatasin-iii has the potential to interfere with nh4+ uptake in birch (betula pendula ... | 2001 | 12060282 |
| characterization of substrate specificity of plant fata and fatb acyl-acp thioesterases. | the specificity of plant acyl-acyl carrier protein (acp) thioesterases is the major determinant of the chain length and level of saturated fatty acids found in most plant tissues. although these enzymes have been previously characterized from a number of sources, information on kinetic parameters for a wide range of substrates with cloned enzymes is lacking. in the present study the substrate specificity of recombinant fata thioesterase isoforms from arabidopsis (atfata) and coriander (csfata) a ... | 2002 | 12061798 |
| molecular and biochemical analysis of serine acetyltransferase and cysteine synthase towards sulfur metabolic engineering in plants. | serine acetyltransferase (satase) and cysteine synthase (o-acetylserine (thiol)-lyase) (csase) are committed in the final step of cysteine biosynthesis. six cdna clones encoding satase have been isolated from several plants, e.g. watermelon, spinach, chinese chive and arabidopsis thaliana. feedback-inhibition pattern and subcellular localization of plant satases were evaluated. two types of satase that differ in their sensitivity to the feedback inhibition by l-cysteine were found in plants. in ... | 2002 | 12083067 |
| phytotoxic compounds from prionosciadium watsoni. | bioassay-guided fractionation of a phytotoxic extract of prionosciadium watsoni led to the isolation of three new pyranocoumarins and two pyranochromones. the new compounds were characterized as propionic acid (9r,10r)-9-acetoxy-8,8-dimethyl-9,10-dihydro-2h,8h-benzo[1,2-b:3,4-b']dipyran-2-one-10-yl ester (1), isobutyric acid (9r,10r)-9-hydroxy-8,8-dimethyl-9,10-dihydro-2h,8h-benzo[1,2-b:3,4-b']dipyran-2-one-10-yl ester (2), isobutyric acid (9r)-8,8-dimethyl-9,10-dihydro-2h,8h-benzo[1,2-b:3,4-b'] ... | 2002 | 12088423 |
| unique fluorescence properties of a cyanobacterium gloeobacter violaceus pcc 7421: reasons for absence of the long-wavelength psi chl a fluorescence at -196 degrees c. | we investigated the reason for the absence of the long-wavelength psi chl a fluorescence at -196 degrees c in the cyanobacterium gloeobacter violaceus using two methods: p-nitrothiophenol (p-ntp) treatment and time-resolved fluorescence spectra. the p-ntp treatment showed that psii chl a fluorescence was specifically affected in a manner similar to that for synechocystis sp. pcc 6803 and spinach chloroplasts, although there were no components modified by the p-ntp treatment, indicating an absenc ... | 2002 | 12091711 |
| effect of domestic processing and cooking methods on total, hcl extractable iron and in vitro availability of iron in spinach and amaranth leaves. | spinach (spinacia oleracia) and amaranth (amaranthus tricolor) leaves were stored in polyethylene bags and without packing for 24 and 48 hours in a refrigerator at 5 degrees c and 30 degrees c in polyethylene bags. the fresh leaves were also dried (oven and sun), blanched (5, 10 and 15 min) and cooked in an open pan and a pressure cooker. the processed leaves were analysed for total iron, its availability and antinutrient content. the iron content of these leaves varied from 26.54 to 34.14 mg/10 ... | 2002 | 12102364 |
| eighteen-month-old fischer 344 rats fed a spinach-enriched diet show improved delay classical eyeblink conditioning and reduced expression of tumor necrosis factor alpha (tnfalpha ) and tnfbeta in the cerebellum. | diets high in antioxidant properties are known to reverse some deficits in neuronal and cognitive function that occur in aging animals. antioxidants are also known to reduce levels of proinflammatory factors in the cns. we report here that 6 weeks of a spinach-enriched diet ameliorates deficits in cerebellar-dependent delay classical eyeblink learning and reduces the proinflammatory cytokines tumor necrosis factor alpha (tnfalpha) and tnfbeta in the cerebelli of eyeblink-trained animals. eightee ... | 2002 | 12122042 |
| mutational bisection of the mitochondrial dna stability and amino acid biosynthetic functions of ilv5p of budding yeast. | ilv5p is a bifunctional yeast mitochondrial enzyme required for branched chain amino acid biosynthesis and for the stability of mitochondrial dna (mtdna) and its parsing into nucleoids. the latter occurs when the general amino acid control (gac) pathway is activated. we have isolated ilv5 mutants that lack either the enzymatic (a(-)d(+)) or the mtdna stability function (a(+)d(-)) of the protein. the affected residues in these two mutant classes cluster differently when mapped to the 3-d structur ... | 2002 | 12136009 |
| bacterial expression of the molybdenum domain of assimilatory nitrate reductase: production of both the functional molybdenum-containing domain and the nonfunctional tungsten analog. | assimilatory nadh:nitrate reductase (ec 1.6.6.1), a complex molybdenum-, cytochrome b(557)- and fad-containing protein, catalyzes the regulated and rate-limiting step in the utilization of inorganic nitrogen by higher plants. to facilitate structure/function studies of the individual molybdenum center, we have developed bacterial expression systems for the heterologous production of the 541 residue amino-terminal, molybdenum center-containing domain of spinach nitrate reductase either as a six-h ... | 2002 | 12139973 |
| in vitro reconstitution of the spinach chloroplast cytochrome b6 protein from a fusion protein expressed in escherichia coli. | we have developed a strategy for overproduction of spinach apocytochrome b6 as a fusion protein to maltose-binding protein (mbp) in escherichia coli, using the expression vector pmal-c2. the fusion protein was purified to virtual homogeneity by gel filtration chromatography and the method of insertion of hemes into fusion protein was elaborated. the ambient and low-temperature absorption spectra of the reconstituted cytochrome b6 were similar to those of cytochrome b6 spectra in isolated protein ... | 2002 | 12147358 |
| [cloning and expression of spinach glycolate oxidase in escherichia coli]. | the cdna coding spinach glycolate oxidase (go) was amplified by rt-pcr using the total rna of spinach leaves as the template, and was cloned into cloning vector pmd18-t. after the dna sequence was determined, the go gene was subcloned into e. coli expression vector pbv220, pet-22b(+), ptig-trx and pthiohisc. sds-page analysis revealed that the recombinant e. coli bl21 (de3) (ptig-trx-go) and e. coli bl21 (de3) (pet-22b(+)-go) expressed the predicted 38 kd glycolate oxidase, and the enzyme activi ... | 2002 | 12148286 |
| identifying and characterizing plastidic 2-oxoglutarate/malate and dicarboxylate transporters in arabidopsis thaliana. | we characterized three arabidopsis genes, atpomt1, atpdct1 and atpdct2, localized on chromosome 5 and homologous to spinach chloroplastic 2-oxoglutarate/malate transporter (omt) gene. the yeast-expressed recombinant atpomt1 protein transported malate and 2-oxoglutarate but not glutamate. by contrast, the recombinant atpdct1 protein transported 2-oxoglutarate and glutamate at similar affinities in exchange for malate. these findings suggested that atpomt1 is omt and atpdct1 is a general dicarboxy ... | 2002 | 12154133 |
| supramolecular organization of photosystem i and light-harvesting complex i in chlamydomonas reinhardtii. | we report a structural characterization by electron microscopy and image analysis of a supramolecular complex consisting of photosystem i and light-harvesting complex i from the unicellular green alga chlamydomonas reinhardtii. the complex is a monomer, has longest dimensions of 21.3 and 18.2 nm in projection, and is significantly larger than the corresponding complex in spinach. comparison with photosystem i complexes from other organisms suggests that the complex contains about 14 light-harves ... | 2002 | 12163173 |
| expression in plants and immunogenicity of plant virus-based experimental rabies vaccine. | a new approach to the production and delivery of vaccine antigens is the use of engineered amino virus-based vectors. a chimeric peptide containing antigenic determinants from rabies virus glycoprotein (g protein) (amino acids 253-275) and nucleoprotein (n protein) (amino acids 404-418) was pcr-amplified and cloned as a translational fusion product with the alfalfa mosaic virus (almv) coat protein (cp). this recombinant cp was expressed in two plant virus-based expression systems. the first one ... | 2002 | 12163267 |
| new sources of dietary myosmine uptake from cereals, fruits, vegetables, and milk. | myosmine has been regarded as a specific tobacco alkaloid until investigations pointed out that nuts and nut products constitute a significant source of myosmine. in the present study it is shown that the occurrence of myosmine is widespread throughout a large number of plant families. using a method for extraction practicable for all examined foods, quantitative analysis through internal standard addition showed nanograms per gram amounts. positively tested edibles were staple foods such as mai ... | 2002 | 12166981 |
| identification of a cis element for tissue-specific alternative splicing of chloroplast ascorbate peroxidase pre-mrna in higher plants. | alternative splicing events in the 3'-terminal region of chloroplast ascorbate peroxidase (chlapx) pre-mrna in spinach and tobacco, which produced four types of mrna variants, one form (tapx-i) encoding thylakoid-bound apx (tapx) and three forms (sapx-i, -ii, and -iii) encoding stromal apx (sapx), were regulated in a tissue-specific manner. the ratio of the level of sapx mrnas (sapx-i, -ii, and -iii) to tapx-i mrna was close to 1 in leaf, whereas the ratio in root was greatly elevated due to an ... | 2002 | 12176976 |
| redox regulation of arabidopsis 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase. | the cdna for 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase of arabidopsis encodes a polypeptide with an amino-terminal signal sequence for plastid import. a cdna fragment encoding the processed form of the enzyme was expressed in escherichia coli. the resulting protein was purified to electrophoretic homogeneity. the enzyme requires mn(2+) and reduced thioredoxin (trx) for activity. spinach (spinacia oleracea) trx f has an apparent dissociation constant for the enzyme of about 0.2 microm. ... | 2002 | 12177500 |
| glu 103 gln site-directed mutation causes an alteration in physical properties of spinach betaine aldehyde dehydrogenase. | site-directed mutant of spinach betaine aldehyde dehydrogenase (badh) was obtained by replacing glu 103 with gln 103 and the resulting e 103 q mutant was expressed in escherichia coli. the mutant badh as compared to the wild-type badh was slightly more sensitive to inhibition by nacl but less sensitive to inhibition by (nh(4))(2)so(4). glycinebetaine (gb) activated the wild-type enzyme but not the mutant enzyme. stronger inhibition by choline was observed in the mutant enzyme than in the wild-ty ... | 2002 | 12186739 |
| gliadin is a good substrate of several transglutaminases: possible implication in the pathogenesis of coeliac disease. | deamidation of distinct glutamines in hla-dq2 restricted gliadin epitopes, considered critical in the pathogenesis of coeliac disease (cd), can be mediated by tissue transglutaminase (ttg). to elucidate the possible role of other transglutaminases in cd we investigated whether different mammalian, microbial and vegetable transglutaminases can use gliadin as substrate. | 2002 | 12190095 |
| functional characterization of choline monooxygenase, an enzyme for betaine synthesis in plants. | in plants, the first step in betaine synthesis was shown to be catalyzed by a novel rieske-type iron-sulfur enzyme, choline monooxygenase (cmo). although cmo so far has been found only in chenopodiaceae and amaranthaceae, the recent genome sequence suggests the presence of a cmo-like gene in arabidopsis, a betaine non-accumulating plant. here, we examined the functional properties of cmo expressed in escherichia coli, cyanobacterium, and arabidopsis thaliana. we found that e. coli cells in which ... | 2002 | 12192001 |
| accumulation of heavy metals in water spinach (ipomoea aquatica) cultivated in the bangkok region, thailand. | the aquatic plant water spinach (ipomoea aquatica), either wild or cultivated, is found throughout southeast asia and is a widely consumed vegetable in the region. many of the waters where i. aquatica grows serve as recipients for domestic and other types of wastewater. because these waters contain not only nutrients, but often also a wide variety of pollutants such as heavy metals from various human activities, many people risk intoxication. to estimate the accumulation of lead (pb), cadmium (c ... | 2002 | 12206434 |
| respiratory chain supercomplexes of mitochondria and bacteria. | respiratory chain complexes are fragments of larger structural and functional units, the respiratory chain supercomplexes or "respirasomes", which exist in bacterial and mitochondrial membranes. supercomplexes of mitochondria and bacteria contain complexes iii, iv, and complex i, with the notable exception of saccharomyces cerevisiae, which does not possess complex i. these supercomplexes often are stable to sonication but sensitive to most detergents except digitonin. in s. cerevisiae, a major ... | 2002 | 12206908 |
| crystal structure of oxyb, a cytochrome p450 implicated in an oxidative phenol coupling reaction during vancomycin biosynthesis. | gene-inactivation studies point to the involvement of oxyb in catalyzing the first oxidative phenol coupling reaction during glycopeptide antibiotic biosynthesis. the oxyb gene has been cloned and sequenced from the vancomycin producer amycolatopsis orientalis, and the hemoprotein has been produced in escherichia coli, crystallized, and its structure determined to 1.7-a resolution. oxyb gave uv-visible spectra characteristic of a p450-like hemoprotein in the low spin ferric state. after reductio ... | 2002 | 12207020 |
| [beta]-1,3-glucanase is cryoprotective in vitro and is accumulated in leaves during cold acclimation. | we have used isolated spinach (spinacea oleracea l.) thylakoid membranes to investigate the possible cryoprotective properties of class i [beta]-1,3-glucanase (1,3-[beta]-d-glucan 3-glucanohydrolase; ec 3.2.1.39) and chitinase. class i [beta]-1,3-glucanase that was purified from tobacco (nicotiana tabacum l.) protected thylakoids against freeze-thaw injury in our in vitro assays, whereas class i chitinase from tobacco had no effect under the same conditions. the [beta]-1,3-glucanase acted by red ... | 1997 | 12223761 |
| antioxidant properties of differently processed spinach products. | the effect of variously processed spinach products (whole-leaf, minced and enzymatically liquefied spinach) on lipid oxidation was determined. in an autoxidative methyl linoleate (melo) system the inhibition of hydroperoxide formation, measured by hplc after three days of oxidation, was in descending order: whole-leaf > liquefied > minced spinach. the inhibition of formation of thiobarbituric acid-reactive substances (tbars) and hexanal by spinach was determined in cooked meatballs with added sp ... | 2002 | 12224427 |
| rna-binding characteristics of a ribonucleoprotein from spinach chloroplast. | a chloroplast (nuclear-encoded) rna-binding protein (28rnp) was previously purified from spinach (spinacia oleracea). this 28rnp was found to be the major rna-binding protein co-purified during the isolation scheme of 3[prime] end rna-processing activity of several chloroplastic genes. to learn more about the possible involvement of 28rnp in the 3[prime] end rna-processing event, we investigated the rna-binding properties and the location of the protein in the chloroplast. we found that recombin ... | 1995 | 12228413 |
| assay, purification, and partial characterization of choline monooxygenase from spinach. | the osmoprotectant glycine betaine is synthesized via the path-way choline -> betaine aldehyde -> glycine betaine. in spinach (spinacia oleracea), the first step is catalyzed by choline monooxygenase (cmo), and the second is catalyzed by betaine aldehyde dehydrogenase. because betaine aldehyde is unstable and not easily detected, we developed a coupled radiometric assay for cmo. [14c]choline is used as substrate; nad+ and betaine aldehyde dehydrogenase prepared from escherichia coli are added to ... | 1995 | 12228495 |