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Although intact fruits of unripe cantaloupe (Cucumis melo L.) produce very little ethylene, a massive increase in ethylene production occurred in response to excision. The evidence indicates that this wound ethylene is produced from methionine via 1-aminocyclopropanecarboxylic acid (ACC) as in ripening fruits. Excision... |
Excised 7-day-old oat (Avena sativa L. cv. Jaycee) leaves were incubated in media containing 7.1 millimolar KNO(3) and 0.15 millimolar tabtoxin or 1 millimolar methionine sulfoximine (MSO) to investigate the sources of the observed ammonium accumulated. Tabtoxin and MSO are known inhibitors of glutamine synthetase, the... |
Exposure of maize leaves to a 3-hour photoinhibitory treatment (photon flux rate of 2,000 microeinsteins meter(-2) second(-1), CO(2)-free air) resulted in lower activities of the light-activated enzymes NADP malate dehydrogenase, pyruvate, Pi dikinase, and ribulose-5-phosphate kinase. The activities could be recovered ... |
The polyamines putrescine, spermidine, and spermine and their biosynthetic enzymes arginine decarboxylase, ornithine decarboxylase and S-adenosyl-l-methionine decarboxylase are present in all parts of dormant potato (Solanum tuberosum L.) tubers. They are equally distributed among the buds of apical and lateral regions... |
Malate dehydrogenase may interfere with the assay of NAD malic enzyme, as NADH is formed during the conversion of malate to oxaloacetate. During the present study, two additional effects of malate dehydrogenase were investigated; they are evident only if the malate dehydrogenase reaction is allowed to reach equilibrium... |
Chromatin-bound poly(adenosine 5'-diphosphate [ADP]-ribose) synthetase activity was highest in ungerminated wheat (Triticum aestivum L., cv. Mukakomugi) embryos, and it decreased after germination within 14 hours. In contrast, transcriptional activity was lowest in ungerminated wheat embryos, and it increased during ge... |
Methods were developed and extended to enable the incubation of isolated barley (Hordeum vulgare cv. Himalaya) aleurone layers under carefully controlled conditions for studies on effects of ethylene on amylase synthesis and release. When layers in medium containing gibberellic acid were exposed to ethylene, the synthe... |
Biochemical and physiological parameters associated with nitrogen metabolism were measured in nodules and roots of glasshouse-grown clones of two symbiotically ineffective alfalfa (Medicago sativa L.) genotypes supplied with either NO(3) (-) or NH(4) (+). Significant differences were observed between genotypes for nodu... |
Embryogenic date palm (Phoenix dactylifera L. var. Medjool) callus cultures were treated with a cryoprotective mixture of polyethylene glycol (Carbowax 6000), glucose, and dimethylsulfoxide (10%/8%/10%, w/v); treated with the mixture, frozen to -196 degrees C, and then thawed; or left untreated. Growth subsequent to tr... |
Soybean (Glycine max L.) seeds contain a galactose-binding protein which displays two activities: (a) an alpha-galactosidase activity and (b) a hemagglutinin activity. The alpha-galactosidase-hemagglutinin was purified to homogeneity by conventional protein purification procedures and also by affinity chromatography. T... |
Kaurene synthetase B activity (conversion of copalyl pyrophosphate to ent-kaurene) is readily detectable in crude cell-free extracts of 3- to 4-day old dark-grown sunflower (Helianthus annuus cv. Mammoth) seedlings, whereas little or no kaurene synthetase AB activity (conversion of geranylgeranyl pyrophosphate to ent-k... |
A crude membrane fraction from Chlamydomonas reinhardii was found to catalyze d-galactose transfer from UDP-galactose to endogenous proteins. Highest incorporation rates were achieved by incubation at 25 degrees C and pH 7.5 in the presence of 10 millimolar Fe(2+). Hydrolytic studies on the labeled polymer revealed tha... |
The plastid and cytosolic isozymes of the dimeric enzyme phosphoglucose isomerase (EC 5.3.1.9) from spinach (Spinacia oleracea) and cauliflower (Brassica oleracea) were purified to apparent homogeneity. The isozymes from sunflower (Helianthus annuus) and Clarkia xantiana were partially purified. When subunits from two ... |
The conversion of fructose-1,6-bisphosphate to glycerate-3-phosphate (PGA) was studied in a reconstituted spinach (Spinacia oleracea L.) chloroplast preparation to determine whether a chloroplast-localized NAB(P)H-oxidizing system (Kow, Smyth, Gibbs 1982 Plant Physiol 69: 72-76 with substrates of ascorbate, NAD(P)H, an... |
In vitro activation of dark-inactivated pyruvate, orthophosphate dikinase extracted from maize (Zea mays L. cv. Golden Cross Bantam T51) leaves was examined. The inactive form of the enzyme and orthophosphate behaved kinetically as substrates for the reaction, which was catalyzed by an activating factor. This factor wa... |
Mesophyll cells and bundle sheath strands isolated from leaves of the C(4) plant Digitaria sanguinalis (L.) Scop. are capable of utilizing aspartate as a Hill oxidant. The resulting O(2) evolution upon illumination depends on the presence of 2-oxoglutarate, is inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea, and i... |
The possibility that plant membrane-bound MgATPases may act as electrogenic proton pumps has been investigated. Using an oat (Avena sativa L. cv. Victory) root membrane preparation which is partially enriched in tightly sealed vesicles, we have shown that MgATP stimulates the uptake of the membrane-permeable anion [(14... |
Within 8 to 10 minutes of illumination, chloroplast thylakoids of pea (Pisum sativum) became enriched 30 to 100% in ribosomes bound by nascent chains. Following (or, in some experiments, coincident with) this apprarent redistribution was a 25 to 65% increase in the total bound ribosome population, which was then mainta... |
2,4-Dichlorophenoxyacetic acid (2,4-D) stimulated the formation of scopoletin and scopolin in tobacco (Nicotiana tabacum L. ;Bright Yellow') cell culture. It especially stimulated the uptake of scopoletin from culture medium into the cells and the glucosylation of scopoletin to its monoglucoside, scopolin. This phenome... |
Elemental composition and distribution of the mineral reserves in the endosperm and embryo tissues of Ricinus communis cultivars Hale and Zanzibarensis were investigated. Energy dispersive x-ray analysis was used to determine the elemental composition of the globoid crystals, while atomic absorption spectrometry allowe... |
Ferredoxin-dependent glutamate synthase (EC 1.4.7.1) from rice leaves (Oryza sativa L. cv Delta) was purified 206-fold with a final specific activity of 35.9 mumoles glutamate formed per min per milligram protein by a procedure including ammonium sulfate fractionation, DEAE-cellulose chromatography, Sephacryl S-300 gel... |
Pectate lyase was isolated from the cell extract of Erwinia aroideae. The enzyme was further purified to a high degree by a procedure involving ammonium sulfate fractionation and chromatography on CM-Sephadex C-50 and on Sephadex G-200. The enzyme attacked its substrate in an endo fashion and was more active on the sod... |
Nitrogen isotope fractionation by Pearl Millet (Pennisetum americanum L. and P. mollissimum L.) grown on nitrate was associated with nitrate reductase activity. Fractionation was evidenced at the step of nitrate reduction when the substrate-to-enzyme ratio was high (possibly saturating for the active sites of the nitra... |
Mitochondria were isolated from spinach (Spinacia oleracea L.) leaves using a Percoll gradient step. The high purity of the organelle fraction is demonstrated by electron microscopy and biochemical parameters. In the matrix space of these mitochondria, a short-chain acyl-coenzyme A hydrolase is present that converts ac... |
Changes in genome expression during normal cellular and plastid development in the first leaf of young (7-day-old) wheat (Triticum aestivum var. Maris Dove) were investigated by examining homogeneous populations of leaf cells and plastids of several developmental ages present in the same leaf. The cells were characteri... |
Intact mitochondria were prepared from spinach (Spinacia oleracea L. var. Kyoho) leaf protoplasts and purified by Percoll discontinuous gradient centrifugation. Assays of several marker enzymes showed that the final mitochondrial preparations obtained are nearly free from other contaminating organelles, e.g. chloroplas... |
As part of an extensive analysis of the factors regulating photosynthesis in Agropyron smithii Rydb., a C(3) grass, we have examined the response of leaf gas exchange and ribulose-1,5-bisphosphate (RuBP) carboxylase activity to temperature. Emphasis was placed on elucidating the specific processes which regulate the te... |
When the protoplasts of peeled oat leaf segments (Avena sativa L.) expand after a brief plasmolysis (osmotic shock), fusicoccin-enhanced H(+) excretion is reduced and protein is released to the rehydration medium. This shock protein seems to arise from the cell surface, not from the interior of leaky cells or from brok... |
The metabolism of l-menthone, which is synthesized in the epidermal oil glands of peppermint (Mentha piperita L. cv. Black Mitcham) leaves, is compartmented; on leaf maturity, this ketone is converted to l-menthol and l-menthyl acetate in one compartment, and to d-neomenthol and d-neomenthyl glucoside in a separate com... |
By polyacrylamide gel electrophoresis, DEAE Sephacel, and hydroxyapatite chromatography, one form of glutamine synthetase has been identified in spinach (Spinacia oleracea L. cv. Monstrueux de Viroflay) leaves. It is localized only inside the chloroplast. The enzyme was purified to homogeneity and specific antibodies a... |
Lysine-ketoglutarate reductase activity was detected and characterized in the developing endosperm of maize (Zea mays L.). The enzyme showed specificity for its substrates: lysine, alpha-ketoglutarate, and NADPH. Formation of the reaction product saccharopine was demonstrated. The pH optimum of the enzyme was close to ... |
The apparent affinity of photosynthesis for inorganic carbon in Anabaena variabilis strain M-3 increased during the course of adaptation from high to low CO(2) concentration (5% and 0.03% v/v CO(2) in air, respectively). This was attributed to an increased ability of the cells to accumulate inorganic carbon during the ... |
The monoterpene ketone l-menthone is specifically converted to l-menthol and l-menthyl acetate and to d-neomenthol and d-neomenthyl-beta-d-glucoside in mature peppermint (Mentha piperita L. cv. Black Mitcham) leaves. The selectivity of product formation results from compartmentation of the menthol dehydrogenase with th... |
The spinach (Spinacia oleracea) leaf sucrose-phosphate synthase was partially purified via DEAE-cellulose chromatography, and its kinetic properties were studied. Fructose-6-phosphate saturation curves were sigmoidal, while UDPglucose saturation curves were hyperbolic. At subsaturating concentrations of fructose-6-phos... |
Regulation of enzymes of methionine biosynthesis was investigated by measuring the specific activities of O-phosphohomoserine-dependent cystathionine gamma-synthase, O-phosphohomoserine sulfhydrylase, and O-acetylserine sulfhydrylase in Lemna paucicostata Hegelm. 6746 grown under various conditions. For cystathionine g... |
Extraction of spinach (Spinacia oleracea L.) chloroplasts with cholate-asolectin in the absence of Mg(2+) results in the rapid and selective inactivation of O(2) evolution and a partial (30 to 40%) loss of photosystem II (PSII) donor activity without extraction of thylakoid bound Mn ( approximately 5 to 6 Mn per 400 Ch... |
A large portion of the gibberellic acid (GA(3))-induced alpha-amylase in isolated aleurone layers is transported into the incubation medium. In the presence of GA(3) and ethylene, an even larger portion of the enzyme is found in the medium. Employing an acid washing technique developed by Varner and Mense (Plant Physio... |
The decline in ethylene production in apple (Pyrus malus L. cv. Golden Delicious) tissue slices during 24 hours incubation in 600 millimolar sorbitol and 10 millimolar 2-(N-morpholino)ethanesulfonic acid buffer (pH 6.0) is recognized as a senescent phenomenon. The inclusion of very high concentrations (100 millimolar) ... |
Photosynthetic carbon fixation is regulated in the chloroplast by the amount of ribulose 1,5-bisphosphate carboxylase which is activated. The activated carboxylase was preserved in detached leaves (barley, maize, soybean, spinach, wheat) for 90 min when stored on ice. With leaf extracts stored at 2 degrees C, the amoun... |
Endopolygalacturonase isolated from culture filtrates of the fungus Rhizopus stolonifer was shown previously to act as an elicitor of biosynthetic capacity for the antifungal agent, casbene, in castor bean (Ricinus communis L.) seedlings (S.-C. Lee, C.A. West 1981 Plant Physiology 67:633-639). Selective amidation of ex... |
NADPH nitrate reductase activity in higher plants has been attributed to the presence of NAD(P)H bispecific nitrate reductases and to the presence of phosphatases capable of hydrolyzing NADPH to NADH. To determine which of these conditions exist in barley (Hordeum vulgare L. cv. Steptoe), we characterized the NADH and ... |
A barley (Hordeum vulgare L.) mutant, nar1a (formerly Az12), deficient in NADH nitrate reductase activity is, nevertheless, capable of growth with nitrate as the sole nitrogen source. In an attempt to identify the mechanism(s) of nitrate reduction in the mutant, nitrate reductase from nar1a was characterized to determi... |
Itachi, a soybean (Glycine max [L.] Merr.) variety with 0.2% normal seed urease activity, was recovered from a screen of 6,000 entries in the United States Department of Agriculture soybean germplasm collection. No urease antigen in Itachi seed extracts was detected by double diffusion or by rocket immunoelectrophoresi... |
Plasma membrane-associated ATPase obtained from cauliflower (Brassica oleraceae L.) florets isolated and assayed by several different procedures was stimulated 150 to 400% by K(+). In contrast, winter wheat (Triticum aestivum L. cv. Kharkov 22 MC) shoot and root ATPase obtained by the same methods exhibited only 10 to ... |
A system has been developed for the study of photosynthetic CO(2) fixation by isolated spinach chloroplasts at air levels of CO(2). Rates of CO(2) fixation were typically 20 to 60 micromoles/milligrams chlorophyll per hour. The rate of fixation was linear for 10 minutes but then declined to less than 10% of the initial... |
Phenotypical temperature adaptation of protein synthesis in wheat (Triticum aestivum L.) seedlings is not affected by darkness (etiolation), by partial inhibition of protein biosynthesis (10(-3)m fluorophenylalanine), or by changing the amino acid precursor and the radioisotope ([(3)H]valine instead of [(14)C]leucine).... |
Acyl-CoA:O-lysophospholipid acyltransferase activity was measured in extracts of developing safflower (Carthamus tinctorius var. UC-1) seeds. Acyltransferase activity was present in all subcellular fractions. The microsomal acyltransferase activity was solubilized with either 30 mm-n-octylglucoside, 1% deoxycholate, or... |
Studies were conducted with 9 to 12 day-old soybean (Glycine max [L.] Merr. cv. Williams) seedlings to determine the contribution of roots to whole plant NO(3) (-) reduction. Using an in vivo -NO(3) (-) nitrate reductase (NR) assay (no exogenous NO(3) (-) added to incubation medium) developed for roots, the roots accou... |
O(2) uptake by tissue extracts in the presence of linoleic acid is generally ascribed to lipoxygenase. Such an O(2) uptake can be observed not only with mitochondria of Solanum tuberosum L. and Arum maculatum L. and pure lipoxygenase but also with cytochrome c. However, the rate of oxidation is highly dependent on the ... |
The electrochemical proton gradient across the tonoplast of isolated (Saccharum sp.) vacuoles and vacuoles in situ was measured. The isolated vacuoles show no significant protonmotive potential difference, the pH gradient of 0.8 (inside acid) was balanced by a membrane potential of about -80 mv (inside negative). From ... |
Amide and ureide biogenic enzymes were measured in the plant fraction of soybean (Glycine max) nodules during the period 11 to 23 days after inoculation with Rhizobium japonicum (USDA 3I1b142). Enzymes involved in the initial assimilation of ammonia, i.e. glutamine synthetase, glutamate synthase, and aspartate aminotra... |
Part of the changes in the hormonal balance involved in plant senescence is due to an auxin limitation. Some of its physiological consequences are studied using pear (Pyrus communis L.) cells cultured in a continuously renewed medium in which 2,4-dichlorophenoxyacetic acid (2,4-D) was absent. In these conditions, an as... |
Proline content increased greatly in detached rice (Oryza sativa cv. Taichung Native 1) leaves during senescence. There was a slight but significant increase in proline level after one day of incubation, and, subsequently, proline accumulated relatively rapidly. By 4 days after excision, the level of proline had increa... |
A plasma-membrane fraction rich in ion-stimulated ATPase activity was isolated from cauliflower (Brassica oleracea L.) buds. The activity of the ATPase was dependent on Mg(2+) and stimulated 4-fold by K(+). The lipids of the membrane fraction contained 57% by weight of phospholipid, 16% glycolipid including sterol glyc... |
The metabolic regulation of membrane lipid composition has been examined using the cell wall-less, unicellular green alga Dunaliella salina (UTEX 1644) as a model system. Low temperature stress was employed to initiate and study the regulatory response.When cultures growing logarithmically at 30 degrees C were chilled ... |
The development of photochemical activity in relation to pigment and membrane protein accumulation in chloroplasts of greening wild-type barley (Hordeum vulgare L. cv. Gateway) and its virescens mutant were studied. The rate of chlorophyll accumulation per plastid was faster in the wild-type than in the mutant seedling... |
Ruptured pea (Pisum sativum cv. Massey Gem) chloroplasts exhibited ascorbate peroxidase activity as determined by H(2)O(2)-dependent oxidation of ascorbate and ascorbate-dependent reduction of H(2)O(2). The ratio of ascorbate peroxidase to NADP-glyceraldehyde 3-phosphate dehydrogenase activity was constant during repea... |
Free polysomes, polysomes released from membranes, and rough microsomal vesicles isolated from developing cotyledons of Pisum sativum L. cv. Burpeeana were used to direct cell-free protein synthesis in a wheat germ system. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that the polypeptide produ... |
Nodulated soybean plants (Glycine max [L.] Merr) were grown in sand culture without combined N or with a continuous supply of nitrate in nutrient solution. Moderate nitrate concentration (30 milligrams N per liter) had little effect on nodule weight/plant while high nitrate concentration (100 milligrams N per liter) de... |
An experimental chemical N-[2-(2-oxo-1-imidazolidinyl)ethyl]-N'-phenylurea (EDU), is an effective protectant against acute and chronic foliar injury due to ozone (0(3)) when sprayed on intact leaves or supplied to the plants through soil application. An 0(3)-sensitive snap bean cultivar (Phaseolus vulgaris L. ;Bush Blu... |
ADPglucose pyrophosphorylase from potato (Solanum tuberosum L.) tubers has been purified by hydrophobic chromatography on 3 aminopropyl-sepharose (Seph-C(3)-NH(2)). The purified preparation showed two closely associated protein-staining bands that coincided with enzyme activity stains. Only one major protein staining b... |
Protein bodies within the endosperm of castor bean (Ricinus communis L. cv. Hale) seeds arise from numerous small vacuoles which progressively become filled with storage protein, of which the crystalloid proteins make up approximately 70%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) shows that ... |
The total cotyledon extract of soybean (Glycine max [L.] Merr. var. Coker 136) seedlings underwent lipolysis as measured by the release of fatty acids. The highest lipolytic activity occurred at pH 9. This lipolytic activity was absent in the dry seeds and increased after germination concomitant with the decrease in to... |
Lipid-linked oligosaccharides were synthesized with the particulate enzyme preparation from mung bean (Phaseolus aureus) seedlings in the presence of GDP-[(14)C] mannose. The oligosaccharides were released from the lipids by mild acid hydrolysis and purified by several passages on Biogel P-4 columns. Five different oli... |
Microsomes from apical buds of pea (Pisum sativum L. var. Téléphone à rames) seedlings hydroxylate lauric acid at the omega-position. This oxidation is catalyzed by a cytochrome P-450 enzyme which differs from laurate hydroxylases previously described in microorganisms and mammals by its strict substrate specificity an... |
Exogenous ethylene stimulated ethylene production in intact citrus (Citrus sinensis L. Osbeck cv. "Washington Navel") leaves and leaf discs following a 24-hour exposure. Studies with leaf discs showed that ethylene production decreased when ethylene was removed by aeration. The extent of stimulation was dependent upon ... |
The biosynthetic mechanism of alpha-amylase synthesis in germinating rice (Oryza sativa L. cv. Kimmazé) seeds has been studied both in vitro and in vivo. Special attention has been focused on the glycosylation of the enzyme molecule. Tunicamycin was found to inhibit glycosylation of alpha-amylase by 98% without signifi... |
Stress ethylene production in bean (Phaseolus vulgaris L., cv. Taylor's Horticultural) leaf tissue was stimulated by Cd(2+) at concentrations above 1 micromolar. Cd(2+)-induced ethylene biosynthesis was dependent upon synthesis of 1-aminocyclopropane-1-carboxylic acid (ACC) by ACC synthase. Activity of ACC synthase and... |
An examination of in vivo polysome-bound activity indicates that soybean (Glycine max, cv. Prize) seed urease is synthesized on large polysomes (n >/= 15). In vitro urease synthesis is directed by a large RNA (3,000-3,300 nucleotides). Urease synthesis occurs throughout the normal protein biosynthetic phase of the deve... |
Inasmuch as the molecule of 1-aminocyclopropanecarboxylic acid (ACC) possesses reflective symmetry but lacks rotational symmetry, the two chemically alike methylene groups can be distinguished by a stereospecific enzyme. To determine whether ACC conversion to ethylene by plant tissues proceeds in a stereospecific fashi... |
Cytidine-diphospho-choline diacyl-glycerol phosphorylcholine phosphotransferase activity was demonstrated in potato (Solanum tuberosum L.) microsomes and the incorporation of cytidine-diphospho[(14)C]choline into phosphatidylcholine was characterized by the time course of (14)C incorporation and the effect of microsoma... |
delta-Aminolevulinic acid (ALA), a key precursor of the tetrapyrroles heme and chlorophyll, is capable of being synthesized by two different routes in cells of the unicellular green alga Euglena gracilis: from the intact carbon skeleton of glutamate, and via the condensation of glycine and succinyl CoA, mediated by the... |
Electron photomicrographs of endosperm tissue from germinating seed of Ricinus communis L. cv. Hale show proplastids which contain prominent starch grains. The content of starch in endosperm tissue increased from 500 micrograms per seed, in imbibed seed, to 1,100 micrograms per seed in 5-day-old seedlings. The maximum ... |
Ornithine carbamoyltransferase, argininosuccinate synthetase, argininosuccinate lyase, and arginase activity were measured in extracts from cotyledons of developing and germinating seeds of Pisum sativum L. The course of activity of these four urea cycle enzymes showed a similar pattern during seed development. The act... |
Sucrose synthase (EC 2.4.1.13) of sugarbeet (Beta vulgaris L.) fibrous roots has a distinctly different order of preference for nucleoside diphosphate substrates than that of the taproot enzyme (Silvius, Snyder 1979 Plant Physiol 64: 1070-1073). Separation and quantitation of UDP, ADP, and GDP in root extracts by high-... |
A plasmalemma-bound NADH oxidation system (Lin 1982 Proc Natl Acad Sci USA 79: 3773-3776) in corn root protoplasts was isolated by a mild treatment of intact protoplasts with trypsin. The majority of NADH stimulated O(2) consumption activity of the protoplasts could be recovered in the supernatant isolated from the int... |
The effect of tungsten on the development of endogenous and nitrate-induced NADH- and FMNH(2)-linked nitrate reductase activities in primary leaves of 10-day-old soybean (Glycine max [L.] Merr.) seedlings was studied. The seedlings were grown with or without exogenous nitrate. High levels of endogenous nitrate reductas... |
ATP sulfurylase was purified extensively from green cabbage (Brassica capitata L.) leaf. The enzyme appears to be an asymmetric dimer composed of 57,000 dalton subunits. Initial velocity and product inhibition studies of the forward and reverse reactions point to an obligately ordered kinetic mechanism with MgATP addin... |
Glyoxylate at a concentration of 10 millimolar caused 50% inhibition of decarboxylation of 20 millimolar [1-(14)C]glycine and accompanying synthesis of serine in a mitochondria-enriched preparation from tobacco (Nicotiana tabacum var. John Williams Broadleaf) leaves. None of the other compounds tested including formate... |
Wheat (Triticum aestivum L. var. Lew) embryonic axes take up externally supplied radioactive amino acid (from a solution greater than 2 millimolar) such that the specific radioactivity of the total internal amino acid rapidly reaches that of the external solution. Nevertheless, incorporation of radioactive amino acid i... |
Studies with purified chloroplasts of Lupinus polyphyllus LINDL. leaflets indicate that the first two enzymes of quinolizidine alkaloid biosynthesis, lysine decarboxylase and 17-oxosparteine synthase, are localized in the chloroplast stroma. Thus, both enzymes share the same subcellular compartment as the biosynthetic ... |
The light activation mechanism of the latent H(+)-ATPase was investigated in intact spinach (Spinacia oleracea, Hybrid 424) chloroplasts. The following observations were made. (a) Photosystem I electron acceptors such as methyl viologen, nitrite, oxaloacetate, etc., inhibit the light activation of the enzyme. (b) The e... |
The effects of freezing and thawing on a cell wall-less mutant (CW15+) of Chlamydomonas reinhardii were investigated by monitoring enzyme release, cell viability, cell ultrastructure, and lipid composition. Cells suspended in Euglena gracilis medium were extremely susceptible to freezing injury, the median lethal tempe... |
In apple (Malus domestica Borkh.) sorbitol is the primary product of photosynthesis, the major translocated form of carbon, and a common fruit constituent and storage compound. Previous work on sorbitol metabolism has revealed a NADPH-dependent aldose 6-phosphate reductase (A6PR) in green tissues, and a NAD-dependent s... |
Microbodies from Mougeotia spec., Strain 168.80 contain aminotransferases for conversion of glyoxylate to glycine and serine to hydroxypyruvate. Formation of glycine is possible at highest rates with alanine and glutamate as amino donors, whereas for deamination of serine, pyruvate and glyoxylate are the most convenien... |
Inosine nucleosidase (EC 3.2.2.2), the enzyme which hydrolyzes inosine to hypoxanthine and ribose, has been partially purified from Lupinus luteus L. cv. Topaz seeds by extraction of the seed meal with low ionic strength buffer, ammonium sulfate fractionation, and chromatography on aminohexyl-Sepharose, Sephadex G-100,... |
Mitochondria isolated from hypocotyls of five-day-old bean (Phaseolus vulgaris L. ;Black Valentine') seedlings rapidly oxidized succinate, malate, and NADH. Oxidation rates, respiratory control, and ADP:O ratios obtained with saturating concentrations of all three substrates indicated that the mitochondria were tightly... |
During the germination of pumpkin (Cucurbita sp. Amakuri Nankin) seeds in dark, the activity of glutamine synthetase in cotyledons gradually increased, reaching a maximum at 5 to 6 days. A measurable enhancement (about 4-fold) of the enzyme activity occurred when the seedlings were exposed to continuous illumination fr... |
The enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase displayed near-maximal activity in isolated, intact barley (Hordeum vulgare L. cv. Pennrad) mesophyll protoplasts. The carboxylase deactivated 40 to 50% in situ when protoplasts were dark-incubated 20 minutes in air-equilibrated solutions. Enzyme activity was f... |
A mutant of Arabidopsis thaliana has been isolated in which ribulose-1,5-bisphosphate carboxylase is present in a nonactivatable form in vivo. The mutation appears to affect carboxylase activation specifically, and not any other enzyme of the photosynthesis or photorespiratory cycles. The effect of the mutation on carb... |
A hydroxyproline-rich glycoprotein was isolated from tobacco (Nicotiana tabacum L.) callus tissue cultures by an acidic-ethanol extraction procedure and purified to about 95% homogeneity by ion exchange chromatography on carboxymethyl cellulose. This glycoprotein agglutinated cells of an avirulent strain (B-1) of the b... |
Bean (Phaseolus vulgaris L. cv. Dwarf) roots were inoculated with Rhizobium phaseoli and colonized by the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus fasciculatum Gerd. and Trappe or left uncolonized as controls. The symbiotic associations were grown in an inert substrate using 0, 25, 50, 100, or 200 milligram... |
3-Phosphoglycerate- and oxaloacetate-dependent O(2) photoevolution by permeabilized cell preparations (Pressates), prepared from wild type (Wt) and two reductive pentose phosphate cycle mutants of Chlamydomonas reinhardtii showed different sensitivities to the inhibitors sodium cyanide and sodium azide. NaCN (1.5 milli... |
Transfer of the nitrogen and carbon of allantoin to amino acids and protein of leaflets, stems and petioles, apices, peduncles, pods, and seeds of detached shoots of nodulated cowpea (Vigna unguiculata L. Walp. cv. Caloona) plants was demonstrated following supply of [2-(14)C], [1,3-(15)N]allantoin in the transpiration... |
Biosynthesis of malate dehydrogenase isoenzymes was studied in cotyledons of watermelons (Citrullus vulgaris Schrad., var. Stone Mountain). The glyoxysomal and mitochondrial isoenzymes are synthesized as higher molecular weight precursors which can be immunoprecipitated by mono-specific antibodies from the products of ... |
To understand the function and membrane origin of ionophore-stimulated ATPases, the activity of nigericin-stimulated ATPase was characterized from a low-density microsomal fraction containing sealed vesicles of autonomous tobacco (Nicotiana tabacum Linnaeous cv. Wisconsin no. 38) callus. The properties of KCl-stimulate... |
Etiolated pea (Pisum sativum cv. Midfreezer) seedlings respond to illumination with white light by changes in the activity of phenylpropanoid and flavonoid synthesizing enzymes. Unlike in cell cultures, changes in enzyme activity in pea seedlings are not concerted. Phenylalanine ammonia-lyase (EC 4.3.1.5) activity peak... |
The correlation between the extractable activities of three key enzymes of assimilatory sulfate reduction and the in vivo incorporation of (35)SO(4) (2-) into amino acids, proteins, and sulfolipids was investigated from greening to senescence in primary leaves of beans (Phaseolus vulgaris L.). The total extractable act... |
The apparent association of ornithine decarboxylase (ODC) with rapid cell proliferation in developing tomato (Lycopersicon esculentum Mill. cv. Pearson ms-35) fruits has been previously described. Further evidence is provided by the use of two ODC inhibitors, alpha-difluoromethylornithine (alpha-DFMO) and alpha-methylo... |
Proline-dependent oxygen uptake in corn mitochondria (Zea mays L. B73 x Mo17 or Mo17 x B73) occurs through a proline dehydrogenase (pH optimum around 7.2) bound to the matrix side of the inner mitochondrial membrane. Sidedness was established by determining the sensitivity of substrate-dependent ferricyanide reduction ... |
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