Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| flow cytometry of spinach chloroplasts : determination of intactness and lectin-binding properties of the envelope and the thylakoid membranes. | intact spinach (spinacia oleracea) chloroplasts, thylakoid membranes, and inside-out or right-side-out thylakoid vesicles have been characterized by flow cytometry with respect to forward angle light scatter, right angle light scatter, and chlorophyll fluorescence. analysis of intact chloroplasts with respect to forward light scatter and the chlorophyll fluorescence parameter revealed the presence of truly "intact" and "disrupted" chloroplasts. the forward light scatter parameter, normally consi ... | 1992 | 16653090 |
| expression of the large atp synthase gene cluster in spinach plastids during light-induced development. | the large atp synthase gene cluster in spinach (spinacia oleracea) plastids encodes four of the six chloroplast-encoded atp synthase subunits. expression of this cluster was examined to determine its response to light-induced plastid development. spinach plastid transcripts were isolated from etiolated tissues, etiolated tissues exposed to 24 h of light, young (1-3 cm) leaves, and mature (8-10 cm) leaves. transcript levels were examined from each developmental stage as a function of either the q ... | 1992 | 16653100 |
| regulation of sucrose phosphate synthase by gibberellins in soybean and spinach plants. | exogenous applications of gibberellins (gas) increased the extractable activity of leaf sucrose phosphate synthase (sps) in soybean (glycine max [l.]) and spinach (spinacia oleracea [l.]). the response to ga applications was detectable within 2 h postapplication and was still observed 6 h, 24 h, and 7 d after treatment. when paclobutrazol, a ga biosynthesis inhibitor, was applied to intact soybean and spinach plants, decreased extractable sps activity resulted within 24 h following the treatment ... | 1992 | 16653111 |
| biochemical characterization of photosystem ii antenna polypeptides in grana and stroma membranes of spinach. | the photosystem (ps) ii antenna system comprises several biochemically and spectroscopically distinct complexes, including light-harvesting complex ii (lhcii), chlorophyll-protein complex (cp) 29, cp26, and cp24. lhcii, the most abundant of these, is both structurally and functionally diverse. the photosynthetic apparatus is laterally segregated within the thylakoid membrane into psi-rich and psii-rich domains, and the distribution of antenna complexes between these domains has implications for ... | 1992 | 16653152 |
| distinctive responses of ribulose-1,5-bisphosphate carboxylase and carbonic anhydrase in wheat leaves to nitrogen nutrition and their possible relationships to co(2)-transfer resistance. | the amounts of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco), total chlorophyll (chl), and total leaf nitrogen were measured in fully expanded, young leaves of wheat (triticum aestivum l.), rice (oryza sativa l.), spinach (spinacia oleracea l.), bean (phaseolus vulgaris l.), and pea (pisum sativum l.). in addition, the activities of whole-chain electron transport and carbonic anhydrase were measured. all plants were grown hydroponically at different nitrogen concentrations. although ... | 1992 | 16653191 |
| species-dependent variation in the interaction of substrate-bound ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) and rubisco activase. | purified spinach (spinacea oleracea l.) and barley (hordeum vulgare l.) ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) activase supported 50 to 100% activation of substrate-bound rubisco from spinach, barley, wheat (triticum aestivum l.), soybean (glycine max l.), pea (pisum sativum l.), arabidopsis thaliana, maize (zea mays l.), and chlamydomonas reinhardtii but supported only 10 to 35% activation of rubisco from three solanaceae species, tobacco (nicotiana tabacum l.), petunia (petu ... | 1992 | 16653209 |
| photosystem ii core phosphorylation heterogeneity, differential herbicide binding, and regulation of electron transfer in photosystem ii preparations from spinach. | the effect of photosystem ii core phosphorylation on the secondary quinone acceptor of photosystem ii (q(b)) domain environment was analyzed by comparative herbicide-binding studies with photosystem ii preparations from spinach (spinacia oleracea l.). it was found that phosphorylation reduces the binding affinity for most photosynthetic herbicides. the binding of synthetic quinones and of the electron acceptor 2,6-dichlorophenolindophenol is also reduced by photosystem ii phosphorylation. four p ... | 1992 | 16653222 |
| light-dependent conversions of endogenous alpha-tocopherylquinone and plastoquinone-d in spinacia oleracea chloroplasts. | 1964 | 16655875 | |
| effect of salts and electron transport on the conformation of isolated chloroplasts. i. light-scattering and volume changes. | whole chloroplasts isolated from the leaves of spinach (spinacia oleracea l.) exhibit 2 types of conformational change during electron transport. amine-uncoupled chloroplasts swell and atebrin-uncoupled chloroplasts shrink. chloroplasts uncoupled by carbonylcyanide phenylhydrazones and by treatment with ethylenediamine tetraacetic acid do not change their volumes or light-scattering properties during electron transport. phosphorylating chloroplasts shrink only slightly.the rate and extent of the ... | 1966 | 16656285 |
| photoinhibition of chloroplast reactions. i. kinetics and action spectra. | a study was made of photoinhibition of spinach chloroplast reactions. the kinetics and spectral characteristics of the photoinhibition over a range between 230 and 700 mmu have been examined. the decline of activity due to preillumination was independent of wavelength, and dependent upon the number of quanta applied, not upon the rate of application. the effectiveness spectra of photoinhibition indicate that active ultraviolet light is absorbed by a pigment which is not a normal light absorber f ... | 1966 | 16656345 |
| chloroplast integrity and atp-dependent co(2) fixation in spinacia oleracea. | washed whole chloroplasts of spinacia oleracea isolated and assayed in a tris (hydroxymethyl aminomethane)-hcl buffered sucrose solution exhibited low dark co(2) fixing activity, whereas washed whole chloroplasts isolated in the same buffer but assayed in that buffer without sucrose exhibited much greater dark co(2) fixing activity. the lowered activity could be attributed to the impermeability of the chloroplast membrane to ribose-5-phosphate or adenosine triphosphate. the preservation of the i ... | 1967 | 16656658 |
| role of aldolase in photosynthesis. ii demonstration of aldolase types in photosynthetic organisms. | spinach leaves and photoautotrophically grown euglena and chlorella possess fructose 1,6-diphosphate aldolases inhibited by p-chloromercuribenzoate but insensitive to k(+) or ethylenediamine tetraacetate (type i). dark grown euglena and chlorella have aldolases inhibited by p-chloromercuribenzoate and ethylenediamine tetraacetate but stimulated by k(+) (type ii). the red alga, chondrus, and the golden-brown alga, ochromonas, appear to possess both types. bean, pea, and spinach seeds and the leav ... | 1968 | 16656841 |
| oxygen evolution and the permeability of the outer envelope of isolated whole chloroplasts. | a rapid oxygraph method of studying the permeability of the envelope of isolated chloroplasts was used. the outer envelope of aqueously isolated whole spinach (spinacia oleracea l.) chloroplasts in buffer is readily permeable to 3-phosphoglyceric acid, which induces an immediate light dependent oxygen evolution. this light dependent oxygen evolution was completely eliminated by swelling these plastids in an osmotically dilute solution. exogenous adenosine diphosphate, but not inorganic phosphate ... | 1968 | 16656943 |
| biogenesis of oxalate in plant tissues. | red beet root discs aerated in potassium phosphate for 2 to 3 days and young spinach leaves actively produce oxalate. a series of labeled compounds was supplied to each of these tissues to determine the extent of conversion to oxalate. similar results were obtained with the 2 tissues except that in the leaf tissue glyoxylate and glycolate were outstandingly good precursors. carbon from glucose, acetate, and particularly from some acids of the tricarboxylic acid cycle was recovered in oxalate. ex ... | 1968 | 16656975 |
| enzyme activities of the carbon reduction cycle in some photosynthetic organisms. | profile analyses of the enzymes comprising the photosynthetic carbon reduction cycle have been performed in extracts of dark grown and greening euglena gracilis var. bacillaris. chlorella pyrenoidosa grown photoautotrophically, in the light with glucose or in the dark with glucose, tolypothrix tenuis, chromatium and leaves of spinach. amounts of activity are compared with the level of photosynthetic co(2) fixation. only in chromatium were all enzyme activities sufficient to support the in vivo r ... | 1969 | 16657059 |
| photosynthetic light reactions in chemically fixed anacystis nidulans, chlorella pyrenoidosa, and porphyridium cruentum. | the photochemical activities of various species of unicellular algae (anacystis nidulans, chlorella pyrenoidosa, and porphyridium cruentum) were studied following chemical fixation. fixation with formaldehyde and glutaraldehyde yielded cells which retained their ability to perform photosystem i and photosystem ii reactions. the photochemical efficiencies of some fixed algae are as great as those of unfixed spinach chloroplasts. fixed algae containing accessory pigments appear to be useful models ... | 1969 | 16657097 |
| inhibition of photosynthesis by oxygen in isolated spinach chloroplasts. | the inhibition of photosynthetic co(2) fixation by o(2), commonly referred to as the warburg effect, was examined in isolated intact spinach (spinacia oleracea) chloroplasts. the major characteristics of this effect in isolated chloroplasts are rapid reversibility when o(2) is replaced by n(2), an increased inhibition by o(2) at low concentrations of co(2) and a decreased effect of o(2) with increased concentrations of co(2).both the dpn- and tpn-linked glyceraldehyde 3-phosphate dehydrogenases ... | 1969 | 16657176 |
| on the molecular identity of esr signal ii observed in photosynthetic systems: the effect of heptane extraction and reconstitution with plastoquinone and deuterated plastoquinone. | speculation as to the identity of signal ii, the light-induced, broad, slow decaying electron spin resonance signal with hyperfine structure observed in photosynthetic materials, has tended to center on the semiquinone of plastoquinone. experiments reported here were designed to give direct evidence bearing on that speculation. heptane extraction of lipids from lyophilized spinach and tobacco chloroplast fragments reduced the amplitude of signal ii and increased the ratio of signal i:signal ii. ... | 1969 | 16657222 |
| photophosphorylation during chloroplast development in red kidney bean. i. characterization of the mature system and the effect of bsa and sulfhydryl reagents. | optimal conditions were determined for photophosphorylation and reduction in mature chloroplasts from phaseolus vulgaris var. red kidney. bovine serum albumin (bsa) at 1 mg/ml and various sulfhydryl reagents (0.1-0.5 mm) greatly enhanced cyclic and noncyclic phosphorylation, but had little effect on photoreduction. bsa and reduced glutathione also stimulated cyclic phosphorylation in spinach chloroplasts. bsa was needed in the reaction from the start to provide high rates of phosphorylation. bsa ... | 1969 | 16657234 |
| some effects of triton x-100 on pea etioplasts. | when pea etioplast preparations were treated with triton x-100, the membranes disappeared, the pigments were solubilized, and the organelles appeared to disintegrate. low speed centrifugation (2000g) of the preparations following treatment with triton x-100 resulted in a pellet which contained considerable quantities of plastid material. this included rna polymerase and dna polymerase activity, much of the dna, about 30% of the rna, and 50% of the protein of the washed plastid. the amount of rna ... | 1970 | 16657482 |
| a lipid requirement for photosystem i activity in heptane-extracted spinach chloroplasts. | a lipid requirement for photosystem i activity in spinacia oleracea chloroplasts has been characterized. the transfer of electrons from tetramethyl-p-phenylenediamine through the chloroplast photosystem to viologen dye was used as an assay of photosystem i activity. activity is diminished by prolonged heptane extraction and is partially restored by readdition of the extracted lipid. extracted chloroplasts require plastocyanin for maximal restoration of activity. the effect of lipid extract in re ... | 1971 | 16657568 |
| isolation of mesophyll cells and bundle sheath cells from digitaria sanguinalis (l.) scop. leaves and a scanning microscopy study of the internal leaf cell morphology. | a technique is described for the separation of mesophyll and bundle sheath cells from digitaria sanguinalis leaves and evidence for separation is given with light and scanning electron micrographs. gentle grinding of fully differentiated leaves in a mortar releases mesophyll cells which are isolated on nylon nets by filtration. more extensive grinding of the remaining tissue yields bundle sheath strands which are isolated by filtration with stainless steel sieves and nylon nets. further grinding ... | 1971 | 16657571 |
| effects of photoperiod on growth rate and endogenous gibberellins in the long-day rosette plant spinach. | the earliest visible responses of spinach plants (spinacia oleracea l., cv. savoy hybrid 612) transferred from short to long days (8 hours of high intensity light supplemented with 16 hours of low intensity illumination from incandescent lamps) were upright leaf orientation and increased elongation of the petioles. the effect of long days on growth rate was direct; i.e., there was no after-effect if the plants were transferred to short days. gibberellin a(3) applied to plants under short days ha ... | 1971 | 16657712 |
| (+)-abscisic acid content of spinach in relation to photoperiod and water stress. | levels of (+)-abscisic acid present in the long-day plant spinach (spinacia oleracea l., cv. savoy hybrid 612) grown under different photoperiodic regimes were measured in purified extracts by optical rotary dispersion. when plants were transferred from short to long days, the abscisic acid content increased 2- to 3-fold. this rise in the level of abscisic acid took place during the 1st long day. abscisic acid levels of plants under short days as well as under long-day conditions were higher at ... | 1971 | 16657741 |
| the effect of freezing on thylakoid membranes in the presence of organic acids. | the effect of salts of organic acids on washed and non-washed chloroplast membranes during freezing was investigated. thylakoids were isolated from spinach leaves (spinacia oleracea l.) and, prior to freezing, salts of various organic acids or inorganic salts or both were added. freezing occurred for 3 to 4 hours at -25 c. after thawing membrane integrity was investigated by measuring the activity of cyclic photophosphorylation.at very low nacl levels (1 to 3 mm, washed thylakoids) salts of orga ... | 1971 | 16657754 |
| inhibition of glycolipid biosynthesis in chloroplasts by ozone and sulfhydryl reagents. | the metabolism of uridine 5'-pyrophosphate-galactose by spinach (spinacia oleracea) chloroplast preparations was inhibited by ozone. the formation of digalactosyl diglyceride and trigalactosyl diglyceride was inhibited much more than the formation of monogalactosyl diglyceride, steryl glycoside, and acylated steryl glycoside. essentially identical results were obtained when glycolipid synthesis was inhibited by n-ethyl maleimide, p-hydroxymercuribenzoate, and cdcl(2). iodoacetate and iodoacetami ... | 1971 | 16657793 |
| effect of antimycin a on photosynthesis of intact spinach chloroplasts. | low concentrations (0.5-10 mum) of antimycin a were shown to increase the rate of co(2) fixation, o(2) evolution and inorganic phosphate esterification in intact spinach (spinacia oleracea) chloroplasts. the increase was highest when the light intensity was saturating. stimulation was independent of the bicarbonate concentration and was accompanied by an enhancement in the synthesis of glycerate 3-phosphate with a decrease in dihydroxyacetone phosphate. the antibiotic decreased the michaelis con ... | 1971 | 16657816 |
| 3-phosphoglycerate phosphatase in plants: iii. activity associated with starch particles. | a particulate form of 3-phosphoglycerate phosphatase represents about 20% of this activity in spinach (spinacia oleracea var. longstanding bloomsdale) leaves. by differential and isopycnic sucrose density gradient centrifugation, all the particulate activity was found in starch grains that pelleted through 2.5 m sucrose. this particulate phosphatase was extremely stable, had a ph optimum of 5.8, and an apparent michaelis constant (3-phosphoglycerate) of 9 x 10(-4)m. no cation requirement for act ... | 1971 | 16657823 |
| inhibition of photosynthetic carbon dioxide fixation in isolated spinach chloroplasts exposed to reduced osmotic potentials. | reduced osmotic potentials inhibited the rate of co(2) fixation by isolated intact spinach (spinacia oleracea) chloroplasts. this inhibition was observed immediately after transfer of chloroplasts from a solution containing 0.33 m sorbitol to higher sorbitol concentrations, and the depressed rate remained constant. the inhibited co(2) fixation could not be attributed to a decreased rate of photosynthetic electron transport, since nadp reduction was unaffected by subjecting the chloroplasts to lo ... | 1971 | 16657842 |
| involvement of photosynthetic carbon reduction cycle intermediates in co(2) fixation and o(2) evolution by isolated chloroplasts. | the photosynthetic carbon reduction cycle intermediates can be divided into three classes according to their effects on the rate of photosynthetic co(2) evolution by whole spinach (spinacia oleracea) chloroplasts and on their ability to affect reversal of certain inhibitors (nigericin, arsenate, arsenite, iodoacetate, antimycin a) of photosynthesis: class i (maximal): fructose 1, 6-diphosphate, dihydroxyacetone phosphate, glyceraldehyde-3-phosphate, ribose-5-phosphate; class 2 (slight): glucose ... | 1971 | 16657865 |
| inhibition of chloroplast reactions with phenylmercuric acetate. | phenylmercuric acetate is a selective inhibitor of the photosynthetic activities of isolated spinach (spinacia oleracea) chloroplasts. at 5 mum concentration of phenylmercuric acetate, photophosphorylation is inhibited. at 33 mum phenylmercuric acetate, ferredoxin is inactivated. ferredoxin-nadp oxidoreductase is 50% inhibited at 100 mum phenylmercuric acetate. photosystem ii reactions are 50% inhibited at 150 mum phenylmercuric acetate and very much higher cooncentrations-500 mum-are needed to ... | 1972 | 16657964 |
| studies on effect of certain quinones: i. electron transport, photophosphorylation, and co(2) fixation in isolated chloroplasts. | the effect of quinone herbicides and fungicides on photosynthetic reactions in isolated spinach (spinacia oleracea) chloroplasts was investigated. 2,3-dichloro-1,4-naphthoquinone (dichlone), 2-amino-3-chloro-1,4-naphthoquinone (06k-quinone), and 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil) inhibited ferricyanide reduction as well as atp formation. benzoquinone had little or no effect on these reactions. the two reactions showed a differential sensitivity to these inhibitors. dichlone was a s ... | 1972 | 16657965 |
| antimycin a stimulation of rate-limiting steps of photosynthesis in isolated spinach chloroplasts. | changes in levels of metabolites in isolated spinach (spinacia oleracea) chloroplasts seen upon addition of antimycin a suggest that the activities of enzymes mediating several regulated reactions are affected. apparently, the presence of added antimycin a does not increase the level of co(2) in the chloroplasts, nor does it stimulate co(2) fixation by increasing the level of the carboxylation substrate, ribulose-1,5-diphosphate. rather, it appears that antimycin a increases co(2) fixation rate ... | 1972 | 16657971 |
| microbody enzymes and carboxylases in sequential extracts from c(4) and c(3) leaves. | a seven-step sequential grinding procedure was applied to leaves of atriplex rosea, sorghum sudanense, and spinacia oleracea to study the distribution of carboxylases and microbody enzymes. in the extracts from c(4) species there were 7- to 10-fold reciprocal changes in specific activities of ribulose-1, 5-diphosphate carboxylase and phosphoenolpyruvate carboxylase. no such changes occurred in sequential extracts from spinach. no inhibitors of ribulose-1, 5-diphosphate carboxylase were detected ... | 1972 | 16658149 |
| the distribution of carbonic anhydrase and ribulose diphosphate carboxylase in maize leaves. | extraction of maize (zea mays) leaves by progressive grinding under suitably protective conditions yields total carbonic anhydrase activities (4800 units per milligram chlorophyll) comparable to the activity in spinach (spinacia oleracea) leaves. the total ribulose diphosphate carboxylase activity was also equal to or greater than the best literature values for maize. of the total leaf carbonic anhydrase, 72.5% on a chlorophyll basis was present in the mesophyll cells and 14.2% in the bundle-she ... | 1972 | 16658170 |
| acid-bath phosphorylation in heptane-extracted chloroplasts. | when spinach (spinacia oleracea) chloroplast fragments were lyophilized and extracted with n-heptane, acid-bath phosphorylation was significantly reduced. phosphorylation could be restored to these chloroplasts, if the extracted material (containing quinones, carotenoids, and other lipids) was added back to dry preparation before rehydration. the results reported suggest it was not quinones which were required for restoration of acid-bath phosphorylation but lipids. it is suggested that the lipi ... | 1972 | 16658223 |
| reversible abolition of enhancement in isolated spinach chloroplasts. | the photosynthetic evolution of oxygen by isolated chloroplasts of spinacia oleracea l. was studied using a modulated oxygen electrode. the enhancement effect, measured as the increase in the relative quantum yield of 650-nanometer light due to the presence of 710-nanometer light, was profoundly influenced by the concentration of inorganic cations in the bathing medium. chloroplast fragments immersed in a solution containing a very low concentration of mgcl(2) or kcl, did not display enhancement ... | 1972 | 16658263 |
| isolation from rhizobium for factors which transfer electrons to soybean nitrogenase. | rhizobium japonicum grown anaerobically with nitrate produced several factors capable of transferring electrons from spinach chloroplasts lacking photosystem ii to soybean root nodule nitrogenase. the same organism grown aerobically produced no factors with detectable activity. it is concluded that the bacterium is potentially capable of producing these proteins in the low oxygen conditions of the leguminous root nodule. | 1973 | 16658274 |
| activation of polyphenol oxidase of chloroplasts. | polyphenol oxidase of leaves is located mainly in chloroplasts isolated by differential or sucrose density gradient centrifugation. this activity is part of the lamellar structure that is not lost on repeated washing of the plastids. the oxidase activity was stable during prolonged storage of the particles at 4 c or -18 c. the km (dihydroxyphenylalanine) for spinach leaf polyphenol oxidase was 7 mm by a spectrophotometric assay and 2 mm by the manometric assay. polyphenol oxidase activity in the ... | 1973 | 16658308 |
| carotenoid composition of spinach chloroplast grana and stroma lamellae. | stroma lamellae and grana stacks prepared by french press rupture of spinach (spinacia oleracea) chloroplasts contain similar amounts of beta-carotene on a protein basis. the grana fraction has considerably more xanthophylls than does the stroma fraction. total carotenoid to chlorophyll ratios are similar for both fractions. | 1973 | 16658372 |
| differences in lipid composition between undifferentiated and mature maize chloroplasts. | lipid compositions of undifferentiated maize (zea mays) chloroplasts, capable of fixing co(2), were compared with the lipid compositions of mature chloroplasts, which do not fix co(2), located in both the mesophyll and bundle sheath cells. the major lipids found in all three chloroplast types were the glycolipids, monogalactosyl diglyceride and digalactosyl diglyceride, followed by decreasing amounts of sulfolipid, phosphatidyl glycerol, phosphatidyl choline, phosphatidyl inositol, and diphospha ... | 1973 | 16658413 |
| isocitrate lyase in green leaves. | isocitrate lyase (ec 4.1.3.1) has been demonstrated in crude dialyzed extracts of healthy spinach (spinacia oleracea) leaves from commercial sources and wheat (triticum aestivum) and maize (zea mays) leaves stored in darkness in the cold room for 1 week. the products of the reaction were identified as glyoxylate and succinate, the former by its phenylhydrazone, and the latter traced by isotopic labeling and cochromatography. fresh spinach extracts contain a mixture of at least two endogenous inh ... | 1973 | 16658428 |
| response of carbon dioxide fixation to water stress: parallel measurements on isolated chloroplasts and intact spinach leaves. | application of water stress to isolated spinach (spinacia oleracea) chloroplasts by redutcion of the osmotic potentials of co(2) fixation media below -6 to -8 bars resulted in decreased rates of fixation regardless of solute composition. a decrease in co(2) fixation rate of isolated chloroplasts was also found when leaves were dehydrated in air prior to chloroplast isolation. an inverse response of co(2) fixation to osmotic potential of the fixation medium was found with chloroplasts isolated fr ... | 1973 | 16658493 |
| fat metabolism in higher plants: lvii. a comparison of fatty acid-synthesizing enzymes in chloroplasts isolated from mature and immature leaves of spinach. | chloroplasts isolated from immature leaves of spinach (spinacia oleracea) differ in enzyme levels from those isolated from mature leaves. on a chlorophyll basis, immature chloroplast preparations had 5- to 6-fold higher capacity to synthesize fatty acids from 2-(14)c-acetate compared to plastids isolated from mature leaves. this difference was correlated with higher activities for the enzymes, acetyl coenzyme a synthetase, malonyl coenzyme a synthetase, acetyl coenzyme a carboxylase, and oleyl c ... | 1973 | 16658518 |
| zinc deficiency, carbonic anhydrase, and photosynthesis in leaves of spinach. | a shortage in the zinc supply to spinach (spinacia oleracea l.) drastically reduced carbonic anhydrase levels with little effect on net co(2) uptake per unit leaf area, except with the most severe zinc stresses. under these conditions, carbonic anhydrase was below 10% and photosynthesis 60 to 70% of the control levels. when photosynthesis was measured at a range of co(2) supply levels, zinc-deficient leaves were less efficient at 300 to 350 microliters per liter co(2) and above, but the same as ... | 1973 | 16658536 |
| site-specific inhibition of photophosphorylation in isolated spinach chloroplasts by mercuric chloride. | photophosphorylation associated with noncyclic electron transport in isolated spinach (spinacia oleracea) chloroplasts is inhibited to approximately 50% by low concentrations of hgcl(2) (less than 1 mumole hg(2+)/mg chlorophyll) when the electron transport pathway includes both sites of energy coupling. reactions involving only a part of the electron transport system can give a functional isolation of at least two sites coupled to phosphorylation. only one of these sites, located between the oxi ... | 1973 | 16658631 |
| properties of phosphoribulokinase of whole chloroplasts. | the ability of intact spinach (spinacia oleracea) chloroplast preparations to catalyze co(2) fixation and photophosphorylation was examined. under conditions optimal for co(2) fixation, only poor photophosphorylation was observed. conditions optimal for photophosphorylation were found to be highly inhibitory to the co(2)-fixing capacity of the intact chloroplast preparation.a method for following the activity of phosphoribulokinase in the intact chloroplast preparation was developed, and conditi ... | 1974 | 16658663 |
| carbon dioxide fixation in the light and in the dark by isolated spinach chloroplasts. | factors affecting co(2) fixation in the spinach (spinacia oleracea) chloroplast were investigated. free magnesium ions are shown to be highly inhibitory for photosynthetic co(2) fixation in isolated intact spinach chloroplasts. the ph optimum for co(2) fixation is about 8.5 but is dependent upon the reaction medium. conditions are defined under which chloroplasts illuminated in the absence of co(2) accumulate ribulose 1,5-diphosphate, and fix co(2) in a subsequent dark period when high magnesium ... | 1974 | 16658664 |
| biosynthesis of phosphatidylethanolamine by enzyme preparations from plant tissues. | the enzymic utilization of cytidine diphosphoethanolamine in the synthesis of phosphatidylethanolamine is localized in the microsomal fraction of spinach (spinacia oleracea) leaves. the metal ion requirement can be satisfied by mn(2+) (saturation approximately 0.6 mm) or mg(2+) (saturation approximately 25 mm). the enzyme has a ph optimum of 8.0 in the presence of mn(2+) and 7.5 in the presence of mg(2+). a michaelis constant of 20 mum was determined for cytidinediphos-phoethanolamine. enzyme ac ... | 1974 | 16658671 |
| further studies on the bicarbonate stimulation of photophosphorylation in isolated chloroplasts. | the bicarbonate effect in stimulating the rate of photophosphorylation by isolated spinach (spinacia oleracea var. virginia blight-resistant savoy) chloroplasts at a ph below the optimum has been re-examined. its seasonal nature may be related to the hormonal status of the plants. bicarbonate anions stimulate adenosine 5'-triphosphate synthesis if added in the final, adenosine 5'-triphosphate-forming stage of either a postillumination or an acid-base experiment. they also stimulate the membrane- ... | 1974 | 16658679 |
| nitrite assimilation and amino nitrogen synthesis in isolated spinach chloroplasts. | the assimilation of nitrite leading to de novo synthesis of amino nitrogen in a chloroplast-enriched fraction isolated from freshly harvested young spinach (spinacia oleracea l.) leaves was demonstrated. the preparations showed approximately 55% intact chloroplasts as determined by light scattering properties and fixed co(2) at rates of approximately 100 mumoles hr(-1) mg chlorophyll(-1).the chloroplast-enriched fraction contained the enzymes, nitrite reductase and nadph-glutamate dehydrogenase, ... | 1974 | 16658715 |
| levels of (+/-) abscisic acid and xanthoxin in spinach under different environmental conditions. | the levels of the growth inhibitors(+)-abscisic acid and xanthoxin were determined in the long day plant spinach (spinacia oleracea l. cv. savoy hybrid 612) grown under different environmental conditions. when plants were transferred from light to darkness, the (+)-abscisic acid level always decreased, whereas the xanthoxin content did not change. the (+)-abscisic acid content was higher in plants grown under low than under high relative humidity.xanthoxin levels were not affected by photoperiod ... | 1974 | 16658759 |
| the role of galactolipids in spinach chloroplast lamellar membranes: i. partial purification of a bean leaf galactolipid lipase and its action on subchloroplast particles. | a galactolipid lipase has been isolated and partially purified from the chloroplast fraction of the primary leaves of phaseolus vulgaris var. kentucky wonder. the lipase hydrolyzed monogalactosyl diglyceride rapidly and phosphatidyl choline relatively slowly. triolein and p-nitrophenyl stearate were not hydrolyzed.spinach subchloroplast particles were excellent substrates for the lipase. initial rates of fatty acid release from subchloroplast particles at 30 c by the lipase as high as 60 microeq ... | 1974 | 16658772 |
| the azolla, anabaena azollae relationship: i. initial characterization of the association. | cultures of azolla caroliniana willd. free of the symbiotic blue-green alga, anabaena azollae, were obtained by treatment of azolla fronds with a regimen of antibiotics. these symbiontfree plants can be maintained only on medium containing a combined nitrogen source.morphological aspects of the symbiotic association show the confinement of the anabaena azollae within the leaf cavity of the azolla. procedures were established for the isolation of pure preparations of anabaena azollae and azolla c ... | 1974 | 16658796 |
| phosphoenolpyruvate carboxylase from spinach leaf tissue: inhibition by sulfite ion. | phosphoenolpyruvate carboxylase (ec 4.1.1.31), partially purified from spinach (spinacia oleracea) leaves, is inhibited by so(3) (2-) ion. the inhibition is competitive or mixed type with respect to hco(3) (-) (ki = 17 mm), and noncompetitive with respect to phosphoenolpyruvic acid (ki = 11 mm), mg(2+) (ki = 10 mm), and mn(2+) (ki = 2.4 mm). the inhibitory effect of so(3) (2-) is more significant in the presence of mn(2+) than in the presence of mg(2+). l-malate, an inhibitor of phosphoenolpyruv ... | 1974 | 16658799 |
| relationship between the level of adenine nucleotides and the carboxylation activity of illuminated isolated spinach chloroplasts: a study with antimycin a. | the changes in the levels of intact spinach (spinacia oleracea l.) chloroplast adenine nucleotides during the time course of light-dependent co(2) fixation were determined with respect to the effect of antimycin a. this study demonstrated that antimycin a lowered the rate of atp formation during the induction period of carboxylation. while the steady state levels of atp and the energy-charge value also decreased in the presence of antimycin, the concomitant increase of the co(2) fixation activit ... | 1974 | 16658804 |
| isolation of intact plastids from a range of plant tissues. | a technique for the isolation of intact plastids from spinach (spinacia oleracea) and pea (pisum sativum) leaves, pea roots and castor bean (ricinus communis) endosperm is described. this technique involves brief centrifugation of whole homogenates on density gradients. intact plastids were located in the gradient by assaying for triose phosphate isomerase activity. contamination of the plastic peak with mitochondria and microbodies was estimated by measurement of cytochrome oxidase and catalase ... | 1974 | 16658807 |
| immunological and biochemical studies on isozymes of malate dehydrogenase and citrate synthetase in castor bean glyoxysomes. | rabbit gamma-globulin obtained after the injection of solubilized proteins of castor bean (ricinus communis l var. hale) glyoxysomes contains antibodies against some of the glyoxysomal enzymes. the gamma-globulin was shown to inhibit by 50% and 80%, respectively, the in vitro activities of the castor bean glyoxysomal citrate synthetase and malate dehydrogenase. the conditions required for the inactivation are described.the glyoxysomal and mitochondrial citrate synthetase from castor bean endospe ... | 1974 | 16658889 |
| dependence of nitrite reduction on electron transport chloroplasts. | methyl viologen and phenazine methosulfate (photosystem i electron acceptors), 3-(3,4-dichlorophenyl)-1, 1-dimethylurea (dcmu, electron-transport inhibitor), and methylamine (photophosphorylation uncoupler) were used to study the dependence of nitrite reduction on electron transport in chloroplasts.dcmu, methyl viologen, and phenazine methosulfate markedly inhibited, whereas methylamine stimulated no(2) (-) reduction in isolated, intact spinach (spinacia oleracea l.) chloroplasts. the addition o ... | 1974 | 16658912 |
| fat metabolism in higher plants: lxii. stearl-acyl carrier protein desaturase from spinach chloroplasts. | stearyl-acyl carrier protein desaturase (ec 1.14.99.6), present in the stroma fraction of spinach (spinacia oleracea) chloroplasts, rapidly desaturated enzymatically prepared stearyl-acyl carrier protein to oleic acid. no other substrates were desaturated. in addition to stearyl-acyl carrier protein, reduced ferredoxin was an essential component of the system. the electron donor systems were either ascorbate, dichlorophenolindophenol, photosystem i and light, or nadph and ferredoxin-nadp reducta ... | 1974 | 16658913 |
| uptake of bicarbonate ion in darkness by isolated chloroplast envelope membranes and intact chloroplasts of spinach. | bicarbonate uptake by isolated chloroplast envelope membranes and intact chloroplasts of spinach (spinacia oleracea l. var. viroflay) in darkness exhibited a similar dependency upon temperature, ph, time, and concentrations of isolated or attached envelope membranes. this similarity in uptake properties demonstrates the usefulness of the envelope membranes for the study of chloroplast permeability. maximal rates for dark hco(3) (-) uptake by isolated envelope membranes and intact chloroplasts we ... | 1974 | 16658920 |
| photosynthetic activity of spinach chloroplasts after isopycnic centrifugation in gradients of silica. | chloroplast suspensions from spinach (spinacia oleracea l.) were clearly resolved into intact and stripped chloroplasts by isopycnic centrifugation in density gradients of silica sol ("ludox") and polyethlene glycol. the intact chloroplasts fixed co(2) and evolved o(2) more rapidly than the crude suspensions; the stripped chloroplasts were inactive. during the photosynthetic fixation of (14)co(2) in the intact chloroplasts recovered from the gradient, the (14)c label was observed to spread throu ... | 1974 | 16658922 |
| properties of glucosyltransferase and glucan transferase from spinach. | a glucosyl and a glucosyl-glucan transferase activity from spinach (spinacia oleracea l. var. matador) leaves have been partially purified and characterized. the latter activity (fraction 1 after diethylaminoethylcellulose chromatography) is responsible for the transfer of glucosyl as well as of maltosyl, maltotriosyl, and higher homologous residues to glucose giving rise to maltose and the correspondingly larger molecules. this fraction also shows beta-amylase activity. the transfer takes place ... | 1974 | 16658965 |
| an improved method for the isolation of spinach chloroplast envelope membranes. | a three-phase, discontinuous sucrose gradient yielded two distinct fractions of envelope membranes from spinach (spinacia oleracea l.) chloroplasts. their buoyant densities were 1.08 g cm(-3) and 1.11 g cm(-3). electron micrographs showed the lighter and heavier fractions to consist primarily of single and double membranes, respectively. the milligrams of lipid-milligrams of protein ratio for the complete envelope membrane (double membrane fraction) was 1.74. thin layer chromatograms showed that ... | 1974 | 16658971 |
| localization and properties of ribulose diphosphate carboxylase from castor bean endosperm. | a substantial portion of the ribulose 1,5-diphosphate carboxylase activity in the endosperm of germinating castor beans (ricinus communis var. hale) is recovered in the proplastid fraction. the partially purified enzyme shows homology with the enzyme from spinach (spinacia oleracea) leaves, as evidenced by its reaction against antibodies to the native spinach enzyme and to its catalytic subunit. the enzyme from the endosperm of castor beans has a molecular weight of about 500,000 and, with the e ... | 1975 | 16659056 |
| carbonic anhydrase of spinach: studies on its location, inhibition, and physiological function. | carbonic anhydrase activity was determined in spinach (spinacia oleracea) leaf organelles isolated on sucrose density gradients and was found to be predominantly in the intact chloroplast fraction. the small amount of activity associated with the mitochondrial fractions was probably due to intact chloroplast contamination. no activity could be associated with the broken chloroplast or microbody fractions. based upon inhibitor studies, carbonic anhydrase was found to be around 2 mm in the chlorop ... | 1975 | 16659104 |
| photosynthetic activities of spinach leaf protoplasts. | photosynthetic activities of protoplasts isolated from spinach leaf (spinacia oleracea l.) were investigated. the protoplasts were stable up to 9 hr, without loss of the original activity of co(2) fixation (33-75 mumoles co(2)/mg chl.hr) and light-dependent o(2) evolution (33-40 mumoles o(2)/mg chl.hr), when stored in 0.8 m mannitol-0.05 m n-tris (hydroxymethyl)-methylglycine-naoh buffer, ph 7, at 4 c in dark. the optimum ph of 8.5 for co(2) fixation reaction carried out in the present experimen ... | 1975 | 16659152 |
| photosynthetic enhancement studied in intact spinach chloroplasts. | the emerson enhancement effect was evaluated in the intact spinach (spinacia oleracea var. long standing bloomsdale) chloroplast by monitoring the uptake of (14)co(2) during illumination by 640 nm and 720 nm lights. low levels (about 10 mum) of fructose 1,6-diphosphate, ribose 5-phosphate, and glycerate 3-phosphate stimulated the rate of photosynthesis and abolished enhancement values observed in their absence. concentrations of the two sugar phosphates at levels of 1 mm responded similarly. in ... | 1975 | 16659171 |
| transport of metabolites across isolated envelope membranes of spinach chloroplasts. | isolated envelope membranes of spinach chloroplasts (spinacia oleracea l. var. viroflay) exhibited selective permeability. metabolites such as 3-phosphoglycerate, bicarbonate, glyoxylate, and acetate were transported rapidly; 6-phosphogluconate, glycolate, glycine, l-malate, and succinate were intermediate; whereas glucose 6-phosphate, fructose 1,6-diphosphate, and sucrose were hardly transported. transport rates, metabolite accumulations within the membrane vesicles, and the internal water volu ... | 1975 | 16659179 |
| the glyceraldehyde 3-phosphate and glycerate 3-phosphate shuttle and carbon dioxide assimilation in intact spinach chloroplasts. | the regulation of co(2) assimilation by intact spinach (spinacia oleracea) chloroplasts by exogenous nadp-linked nonreversible d-glyceraldehyde-3-phosphate dehydrogenase (ec 1.2.1.9) was investigated. this dehydrogenase mediated a glyceraldehyde 3-phosphate/glycerate 3-phosphate shuttle for the indirect transfer of nadph from chloroplast to the external medium. the rate of nadph formation in the medium reflected glyceraldehyde 3-phosphate efflux from the chloroplast. increasing enzyme concentrat ... | 1975 | 16659203 |
| carbon dioxide assimilation by leaves, isolated chloroplasts, and ribulose bisphosphate carboxylase from spinach. | the relationship between rate of photosynthesis and co(2) concentration has been reinvestigated using isolated spinach (spinacia oleracea) chloroplasts. the apparently low co(2) concentration required for half-maximal photosynthesis is shown to result partly from a ceiling imposed by electron transport. in double reciprocal plots of rate against co(2) concentration, this ceiling results in departures from linearity at high co(2) concentrations. if these rate limitations are disregarded in extrap ... | 1975 | 16659216 |
| h(2) metabolism in photosynthetic organisms: i. dark h(2) evolution and uptake by algae and mosses. | dark h(2) metabolism was studied in marine and fresh water red algae, the green alga, chlamydomonas, and mosses. a time variable and temperature-sensitive anaerobic incubation was required prior to h(2) evolution. h(2) evolution was sensitive to disalicylidenepropanediamine. an immediate h(2) uptake was observed in these algae. immediate dark h(2) uptake but no evolution was observed in the mosses.a cell-free hydrogenase preparation was obtained from anaerobically adapted chlamydomonas reinhardi ... | 1975 | 16659260 |
| metabolic conversion of l-ascorbic acid to oxalic acid in oxalate-accumulating plants. | l-ascorbic acid-1-(14)c and its oxidation product, dehydro-l-ascorbic acid, produced labeled oxalic acid in oxalate-accumulating plants such as spinach seedlings (spinacia oleracea) and the detached leaves of woodsorrel (oxalis stricta and o. oregana), shamrock (oxalis adenopylla), and begonia (begonia evansiana). in o. oregana, conversion occurred equally well in the presence or absence of light. this relationship between l-ascorbic acid metabolism and oxalic acid formation must be given carefu ... | 1975 | 16659288 |
| sulfur dioxide inhibition of photosynthesis in isolated spinach chloroplasts. | photosynthetic oxygen evolution by isolated spinach (spinacia oleracea l.) chloroplasts approached complete inhibition in the presence of a 5 mm concentration of sulfur dioxide. a similar inhibition was observed in the presence of equimolar concentrations of bisulfite ions, suggesting a parallel mode of action. in contrast, an equimolar concentration of sulfite ions was markedly less inhibitory and sulfate ions caused negligible inhibition of apparent photosynthesis. the mode of action of sulfur ... | 1975 | 16659319 |
| relationships between the transition of the physical phase of membrane lipids and photosynthetic parameters in anacystis nidulans and lettuce and spinach chloroplasts. | the transition of the physical phase of lipids in membrane fragments of a blue-green alga anacystis nidulans was studied by a spin labeling technique. the maximum hyperfine splitting of the electron spin resonance spectrum of the n-oxyl-4', 4'-dimethyloxazolidine derivative of 5-ketostearic acid plotted against the reciprocal of the absolute temperature gave a discontinuity point that was characteristic of a transition of the physical phase of the hydrocarbon region of membrane lipids. the phase ... | 1975 | 16659334 |
| ph dependence of the km(co(2)) of ribulose 1,5-diphosphate carboxylase. | the km(co(2)) values of ribulose 1,5-diphosphate carboxylase in freshly ruptured spinach (spinacia oleracea l.) chloroplasts and in the purified form isolated from spinach leaves were found to be ph dependent. raising the ph of the assay solution produced a substantial decrease in the km(co(2)) of both enzyme systems. in freshly ruptured chloroplasts at ph 7.2 the km(co(2)) was 25 mum, at ph 8 it decreased to 19 mum, and at ph 8.8 a further decrease to 7 mum was found. with the purified enzyme a ... | 1975 | 16659359 |
| effect of oxygen on photosynthesis by spinach leaf protoplasts. | the photosynthetic co(2) fixation by spinach leaf (spinacia oleracea l. var. kyoho) protoplasts was inhibited by substituting an atmosphere of n(2) with one of either air (21% o(2)) or 100% o(2). the inhibitory effect of 100% o(2) was greater than that of air. the mode of inhibition by 100% o(2) and air was competitive with respect to co(2); ki(o(2)) value was 0.32 mm at ph 7 and 0.28 mm at ph 8.5 the labeling patterns of compounds in protoplasts exposed to (14)co(2) in light after transferring ... | 1975 | 16659379 |
| temperature dependence of chlorophyll a fluorescence in relation to the physical phase of membrane lipids algae and higher plants. | the temperature dependence of the yield of chlorophyll a fluorescence was measured at room temperatures in living algal cells and higher plant chloroplasts. 3-(3',4'-dichlorophenyl)-1, 1-dimethylurea was added to the samples during the measurements in order to eliminate the influence of photosynthetic photochemical reactions on the fluorescence yield.in anacystis nidulans the maximum in the curve for the fluorescence yield versus temperature occurred near the temperatures at which the transition ... | 1975 | 16659396 |
| chloroplast growth and replication in germinating spinach cotyledons following massive gamma-irradiation of the seed. | spinach seeds (spinacia oleracea l.) given massive doses of gamma-irradiation (500 krad) germinate and form a seedling with two green cotyledons and a radicle, but develop no further. irradiated cotyledons show no increase in cell number or total dna over a 7-day period in the light, while in control cotyledons there is a small increase in cell number and large increases in total dna and chloroplast number. the chloroplasts of irradiated cotyledons are delayed in their division, become greatly e ... | 1976 | 16659421 |
| distribution of protein-bound hexosamine in chloroplasts. | intact chloroplasts of spinach (spinacia oleracea l.), sunflower (helianthus annuus l.), and maize (zea mays l.) mesophyll cells contained 0.33, 0.50, and 0.14% of bound hexosamine on a protein basis, respectively. undifferentiated maize chloroplasts contained 0.19%. values for chloroplast lamellae were, respectively, 0.16, 0.18, 0.12, and 0.06% and for envelope membranes they were 1.6, 2.5, 3.8, and 2.7%. thus most of the hexosamine of chloroplasts is located in the envelope membrane. | 1976 | 16659424 |
| effect of glycidate on glycolate formation and photosynthesis in isolated spinach chloroplasts. | glycidate (2,3-epoxypropionate) increased co(2) photoassimilation in intact spinach (spinacia oleracea l.) chloroplasts in the presence of various inhibitors of photosynthesis, including o(2), arsenite, azide, iodo-acetamide, and carbonylcyanide 3-chlorophenylhydrazone. although the mechanism by which glycidate enhances photosynthesis is obscure, the stimulatory effect cannot be ascribed to either an inhibition of glycolate formation, a specific interaction with the o(2) inhibition of photosynth ... | 1976 | 16659458 |
| effects of ph and oxygen on photosynthetic reactions of intact chloroplasts. | oxygen inhibition of photosynthesis was studied with intact spinach (spinacia oleracea l.) chloroplasts which exhibited very high rates of photosynthetic co(2) reduction and were insensitive to additions of photosynthetic intermediates when co(2) was available at saturating concentrations. photosynthetic rates were measured polarographically as o(2) evolution, and the extent of the reduction of substrate was estimated from the amount of o(2) evolved. with co(2) as substrate, inhibition of photos ... | 1976 | 16659466 |
| isolation and bicarbonate transport of chloroplast envelope membranes from species of differing net photosynthetic efficiency. | a three-phase discontinuous sucrose gradient yielded two fractions of chloroplast envelope membranes from spinach (spinacia oleracea l.), sunflower (helianthus annuus l.), and maize (zea mays l., mesophyll and undifferentiated chloroplasts). these species were selected to represent plants with fast photorespiration and slow net photosynthesis, fast photorespiration yet fast net photosynthesis, and slow photorespiration and fast net photosynthesis, respectively. buoyant densities were 1.08 and 1. ... | 1976 | 16659477 |
| organization of electron transport in photosystem ii of spinach chloroplasts according to chelator inhibition sites. | the organization of electron transport in photosystem ii of spinach (spinacia oleracea) chloroplasts was studied by means of various chelators and uncouplers. the partial reactions used included h(2)o-->methyl viologen, h(2)o-->silicomolybdic acid h(2)o-->ferricyanide, and h(2)o-->dimethylbenzoquinone. three types of chelator inhibition were found (a) inhibition common to all pathways and presumably affecting the mn or water oxidation site in photosystem ii (salicylaldoxime, dithizone, acridine, ... | 1976 | 16659501 |
| alterations in chloroplast thylakoids during an in vitro freeze-thaw cycle. | plastocyanin and chloroplast coupling factor 1 (cf(1)) are released from spinach (spinacia oleracea l.) thylakoids during a slow freezethaw cycle. cf(1) addition increases the proton uptake of thylakoids previously frozen in sucrose concentrations of 15 mm to 100 mm. addition of cf(1) and plastocyanin restores the proton uptake of thylakoids frozen in 100 mm sucrose. plastocyanin and cf(1) release is a manifestation, not the cause, of freeze-thaw damage.frozen-thawed thylakoids appear to exhibit ... | 1976 | 16659550 |
| role of galactolipids in spinach chloroplast lamellar membranes: ii. effects of galactolipid depletion on phosphorylation and electron flow. | a galactolipid lipase from primary bean (phaseolus vulgaris) leaves has been used to partially deplete spinach chloroplast inner membranes of their galactolipids. chloroplasts treated with the lipase in the absence of bovine serum albumin lost 91% of their monogalactosyl diglyceride, 83% of their digalactosyl diglyceride, all of their phosphatidyl choline, but none of their sulfolipid. electron microscopy of this sections revealed that the treated chloroplasts were greatly enlarged and lacked me ... | 1976 | 16659559 |
| photoreduction of sulfur dioxide by spinach leaves and isolated spinach chloroplasts. | labeled sulfur dioxide was found to be extensively absorbed by spinach (spinacea oleracea l.) leaves. labeled sulfides detected in leaf blades following fumigations with sulfur dioxide in light indicated that photoreduction of sulfur dioxide had occurred. measurable proportions of this labeled sulfur was localized within the chloroplast fraction. suspensions of isolated chloroplasts supplied with labeled sulfur dioxide contained labeled sulfides following a 30-minute illumination period in water ... | 1976 | 16659572 |
| starch degradation in isolated spinach chloroplasts. | a method for loading isolated intact spinach (spinacia oleracea l.) chloroplasts with (14)c-starch is described. these intact chloroplasts were incubated aerobically in the dark for 30 minutes. radioactivity in starch declined and glyceric acid 3-phosphate and maltose were the major radioactive products. it is proposed that starch is degraded within the chloroplast to glyceric acid 3-phosphate and to maltose. | 1976 | 16659602 |
| organelle-specific isozymes of aspartate-alpha-ketoglutarate transaminase in spinach leaves. | four distinct isozymes of aspartate-alpha-ketoglutarate transaminase in a spinach (spinacia oleracea l.) leaf extract were separated by starch gel electrophoresis. of the total aspartate-alpha-ketoglutarate transaminase activity, approximately 45% was represented by the chloroplast isozyme, 26% by the cytosol isozyme, 19% by the mitochondrial isozyme, and 3 to 10% by the peroxisomal isozyme. the aspartate-alpha-ketoglutarate transamination activity in the four subcellular compartments behaved si ... | 1976 | 16659609 |
| stimulation of carbon dioxide fixation in isolated pea chloroplasts by catalytic amounts of adenine nucleotides. | carbon dioxide-dependent o(2) evolution by isolated pea (pisum sativum var. massey gem) chloroplasts was increased two to 12 times by the addition of atp. o(2) evolution was also stimulated by adp and to a lesser extent by amp. the atp effects were not due to broken chloroplasts present in the preparations nor was atp acting as a phosphate source. we concluded that the adenine nucleotides were acting catalytically. the concentration of atp required for half-maximum rate of o(2) evolution was 16 ... | 1976 | 16659638 |
| lipid and fatty acid composition of chloroplast envelope membranes from species with differing net photosynthesis. | lipid and fatty acid compositions were determined for chloroplast envelope membranes isolated from spinach (spinacia oleracea l.), sunflower (helianthus annuus l.), and maize (zea mays l.) leaves. the lipid composition was similar in sunflower, spinach, and undifferentiated maize chloroplast envelope membranes and different in maize mesophyll chloroplast envelope membranes. the predominant lipid constituents in all envelope membranes were monogalactosyldiglyceride (27 to 46%), digalactosyldiglyc ... | 1976 | 16659725 |
| nitrite reduction in reconstituted and whole spinach chloroplasts during carbon dioxide reduction. | nitrite reduction in either whole, isolated spinach chloroplasts (spinacia oleracea l.) or in reconstituted spinach chloroplasts is stimulated by a short period of photosynthetic co(2) fixation in the light prior to nitrite addition. with reconstituted chloroplasts, a similar stimulation can be obtained in nitrite reduction without co(2) fixation by the addition of dihydroxyacetone phosphate or fructose 6-phosphate. specific intermediate metabolites of the photosynthetic carbon reduction cycle m ... | 1977 | 16659813 |
| partial analysis of the bands seen in circular dichroism spectra of green and blue-green algal cells and thylakoids. | a comparison was made of the circular dichroism (c.d.) spectra of chlorella, euglena, and anacystis cells and thylakoids. analyses of the spectra reveal that these c.d. bands are similar to those observed previously in whole spinach choloroplasts and subchloroplast particles. c.d. spectra of euglena chloroplasts show bands at longer wavelengths than previously reported. from comparisons of circular dichroism spectra and fine structure, it was concluded that: (a) bands seen in circular dichroism ... | 1977 | 16659816 |
| photosynthesis by isolated pea chloroplasts: some effects of adenylates and inorganic pyrophosphate. | when added singly to chloroplasts isolated from young pea (pisum sativum) leaves, both inorganic pyrophosphate (ppi) and small quantities (0.2 mm) of adp inhibit photosynthesis, but when added together they cause a marked stimulation. atp (at 0.2 mm) is less inhibitory (or not inhibitory) when added alone, but like adp, stimulates when added in the presence of ppi. this behavior is in marked contrast to that of spinach (spinacia oleracea) chloroplasts which are normally stimulated rather than in ... | 1977 | 16659866 |
| evidence for alpha-tocopherol function in the electron transport chain of chloroplasts. | the effect of three different stable radicals-2,2-diphenyl-1-picrylhydrazyl, 1,3,5-triphenyl-verdazyl, and galvinoxyl-was studied in photosystem ii of spinach (spinacia oleracea) chloroplasts. inhibition by the three was noted on dimethylbenzoquinone reduction in presence of 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (dbmib) and on silicomolybdate reduction in presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (dcmu) in photosystem ii and on the h(2)o --> methylviologen reaction encompassi ... | 1977 | 16659867 |
| influence of ph upon the warburg effect in isolated intact spinach chloroplasts: i. carbon dioxide photoassimilation and glycolate synthesis. | the influence of ph upon the o(2) inhibition of (14)co(2) photoassimilation (warburg effect) was examined in intact spinach (spinacia oleracea) chloroplasts. with conditions which favored the warburg effect, i.e. rate-limiting co(2) and 100% o(2), o(2) inhibition was greater at ph 8.4 to 8.5 than at ph 7.5 to 7.8. at ph 8.5, as compared with 7.8, there was an enhanced (14)c-labeling of glycolate, and a decrease of isotope in some phosphorylated calvin cycle intermediates, particularly triose-pho ... | 1977 | 16659887 |
| chloroplast glutathione reductase. | glutathione reductase (ec 1.6.4.2) activity is present in spinach (spinacia oleracea l.) chloroplasts. the ph dependence and substrate concentration for half-maximal rate are reported and a possible role in chloroplasts is proposed. | 1977 | 16659940 |
| inhibition of photosynthesis by azide and cyanide and the role of oxygen in photosynthesis. | cyanide and azide inhibit photosynthesis and catalase activity of isolated, intact spinach (spinacia oleracea) chloroplasts. when chloroplasts are illuminated in the presence of cn(-) or n(3) (-), accumulation of h(2)o(2) is observed, parallel to inhibition of photosynthesis. photosynthetic o(2) evolution is inhibited to the same extent, under saturating light, whether co(2) or phosphoglycerate is present as electron acceptor.the illumination of chloroplasts with cn(-) or n(3) (-) inactivates th ... | 1977 | 16659956 |
| effect of light and chilling temperatures on chilling-sensitive and chilling-resistant plants. pretreatment of cucumber and spinach thylakoids in vivo and in vitro. | the effects of chilling temperatures, in light or dark, on the isolated thylakoids and leaf discs of cucumber (cucumis sativa l. "marketer") and spinach (spinacia oleracea l. "bloomsdale") were studied. the pretreatment of isolated thylakoids and leaf discs at 4 c in the dark did not affect the phenazine methosulfate-dependent phosphorylation, proton uptake, osmotic response to sucrose, ca(2+)-dependent atpase activity, or chlorophyll content. exposure of cucumber cotyledon discs and isolated th ... | 1977 | 16659980 |
| role of orthophosphate and other factors in the regulation of starch formation in leaves and isolated chloroplasts. | starch synthesis in leaves was increased by phosphate starvation or by treatments which decreased cytoplasmic orthophosphate levels (such as mannose feeding). usually less than 30% of the total carbon fixed during co(2) assimilation was incorporated into starch in spinach (spinacia oleracea l.), spinach beet (beta vulgaris), and tobacco (nicotiana tabacum) leaves.in isolated spinach chloroplasts, formation of starch from co(2) was usually less than in leaves. in the absence of significant levels ... | 1977 | 16660011 |