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Query: EC:1.2.1.13 (glyceraldehyde-3-phosphate dehydrogenase)
 6,511 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chloroplast NADP-linked glyceraldehyde-3-phosphate dehydrogenase was resolved into three forms that differed in molecular weight: (a) larger than or equal to 1.5 million; (b) 600,000; and (c) less than or equal to 100,000. After preincubation with an effector (ATP, NADPH, or Pi) the activity of forms a and c was unaffected, whereas the activity of b, the regulatory form, was increased 10-fold. Activation was accompanied by the exposure of previously hidden sulfhydryl groups. The rate of activation was slower than the rate of catalysis and resulted in a lag phase during the measurement of activity when the enzyme was preincubated in the absence of an effector. The addition of one of several compounds as a second effector (at a concentration which itself was nonactivating) in the presence of a first effector enhanced activation by lowering the concentration of the first effector required for half-maximal activation (Pi constant/ATP or NADPH varied; ATP or NADPH constant/Pi varied). Other combinations of effectors caused little change in activity (ATP constant/NADPH varied; NADPH constant/ATP varied). Glyceraldehyde 3-phosphate added as a second effector induced contrasting changes: an increase in the ATP-mediated activation and a decrease in the NADPH-mediated activation. The results are consistent with the view that the products of the photochemical reactions of chloroplasts, ATP, and NADPH, in conjunction with other metabolites, regulate the activity of glyceraldehyde-3-phosphate dehydrogenase in the photosynthetic assimilation of CO2.
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PMID:Studies on the regulation of chloroplast NADP-linked glyceraldehyde-3-phosphate dehydrogenase. 1 Feb 97

NADH-dependent glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.--) of the photosynthetic alga Scenedesmus obliquus is converted to an NADPH specific form by incubation with dithiothreitol. The change in nucleotide specificity is accompanied by a reduction in the molecular weight of the enzyme from 550 000 to 140 000. Prolonged incubation with dithiothreitol results in the further dissociation of the enzyme to an inactive 70 000 dalton species. The 140 000 dalton, NADPH-specific enzyme is stabilized against dissociation and inactivation by the presence of NAD(H) or NADP(H). Optimum stimulation of NADPH-dependent glyceraldehyde-3-phosphate dehydrogenase activity is achieved on incubation of the NADH-specific enzyme with dithiothreitol and NADPH, or dithiothreitol and a 1,3-diphosphoglycerate generating system. The relevance of these observations to in vivo light-induced changes in the nucleotide specificity of the enzyme is discussed.
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PMID:Glyceraldehyde-3-phosphate dehydrogenase of Scenedesmus obliquus. Effects of dithiothreitol and nucleotide on coenzyme specificity. 1 3

Glucose when present as a sole organic carbon source in a mineral salts medium is dissimilated by Caulobacter crescentus ATCC 15252 (strain CB-2) by the Entner-Doudoroff pathway throughout the culture cycle (exponential, transition, and stationary phase). Most of the available glucose that is present at the onset of exponential growth is assimilated by the cells during the transition phase or the period associated with stalk cell development. Swarmer cell development is minimized during this phase. During this same period the pH drops from 6.1 to 4.9 as a result of an abundant excretion of acetic acid. Simultaneously, poly-beta-hydroxybutyrate accumulates within the cells at an accelerated rate. An NADP-dependent glyceraldehyde-3-phosphate dehydrogenase is also present throughout the culture cycle which subsumes the presence of the subsequent enzymes of the Embden-Meyerhof-Parnas pathway in pyruvate formation. An operative tricarboxylic acid cycle is associated with cells throughout the culture cycle.
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PMID:Pathway of glucose catabolism in Caulobacter crescentus. 1 52

A versatile fluorimetric assay based on the reduction of resazurin to resorufin demonstrated high specific activities for a number of important pyridine nucleotide-linked dehydrogenases in tobacco leaves. The Michaelis constant for the important photosynthetic enzyme, D-glyceraldehyde-3-phosphate:NADP+ oxidoreductase (EC 1.2.1.13), determined by the fluorimetric method, was considerably lower than constants determined by conventional extraction and assay methods reported for the enzyme from other plants. The sensitivity of the fluorimetric method enabled the use of dilute enzyme preparations with resultant low background and high substrate specificity. Inclusion of the anti-oxidant diethyldithiocarbamate in the extraction medium preserved the enzymes during extraction. Primary amines inhibited competitively, and phenazine methosulfate non-competitively each of the eight dehydrogenases tested with the fluorimetric assay. The Mn2+ dependence of NADP-linked dehydrogenases specific for isocitrate and malate was confirmed. The method is rapid, requires a simple combination of ingredients and should be useful for surveying dehydrogenase activity in leaves.
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PMID:Fluorimetric assay of tobacco leaf dehydrogenases with resazurin. 2 Sep 57

1. NAD(P)+-induced changes in the aggregational state of prepurified NADP-linked glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.13) were used to isolate the enzyme from Spinacia oleracea, Pisum sativaum and Hordeum vulgare. Each of the three plant species contains two separate isoenzymes. Isoenzyme 1 (fast moving during conventional electrophoresis) precipitates with the ammonium sulfate fraction 55--70% saturation. It shows two separate subunits in dodecylsulfate gels, which are probably arranged as A2B2 in the native enzyme molecule. Isoenzyme 2 (slow moving during conventional electrophoresis) precipitates with the ammonium sulfate fraction 70--95%. It contains a sigle subunit of the same Mr as subunit A in isoenzyme 1 and is apparently a tetramer (A4). The molecular weights of subunits A/B for spinach, peas and barley were determined as 38,000/40,000, 38,000/42,000 and 36,000/39,000 respectively. 2. The NAD-specific glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12) was purified from Spinacia oleracea and Pisum sativum by affinity chromatography on blue Sepharose CL-6B. The enzyme from both plant species is shown to be a tetramer of subunits with Mr 39,000. 3. The present findings contrast with heterogeneous results obtained previously by other authors. These results suggested that there are considerable interspecific differences in the quaternary structure of glyceraldehyde-3-phosphate dehydrogenases from higher plants.
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PMID:Quaternary structure of higher plant glyceraldehyde-3-phosphate dehydrogenases. 3 50

In a previous publication (Cerff, R. (1979) Eur. J. Biochem., 94, 243--247) we demonstrated that chloroplast NADP-linked glyceraldehyde-3-P dehydrogenase (EC 1.2.1.13) from higher plants consists of two separate isoenzymes with apparent subunit compositions A2B2 (isoenzyme 1) and A4 (isoenzyme 2), where Subunits A and B are distinguished by slightly different molecular weights (A smaller than or approximately to B). In the present study we compare isoenzymes 1 and 2 from Sinapis alba and Hordeum vulgare on the basis of antigenic cross-reactivity, tryptic peptides, and amino acid composition. Isoenzymes 1 and 2 show immunochemical identity. They also have very similar tryptic peptide maps and amino acid compositions. This strongly suggests that Subunits A and B of the NADP-linked enzyme are very similar in primary sequence. As opposed to this, cytoplasmic NAD-specific glyceraldehyde-3-P dehydrogenase (EC 1.2.1.12) does not cross-react with antisera raised against the NADP-linked enzyme. Furthermore, tryptic peptide maps of the NAD-specific enzyme show little or no similarity with those of the NADP-linked enzyme. This indicates that the subunits of the NADP-linked enzyme and the subunit of the NAD-specific enzyme are different proteins coded by separate genes. The differences in the amino acid compositions between the two species corresponds to a SdeltaQ value of 21, suggesting some sequence resemblance and a common phylogenetic origin.
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PMID:Subunit structure of higher plant glyceraldehyde-3-phosphate dehydrogenases (EC 1.2.1.12 and EC 1.2.1.13). 10 46

Cell-free extracts of Methanobacterium thermoautotrophicum were found to contain high activities of the following oxidoreductases (at 60 degrees C): pyruvate dehydrogenase (coenzyme A acetylating), 275 nmol/min per mg of protein; alpha-ketoglutarate dehydrogenase (coenzyme A acylating), 100 nmol/min per mg; fumarate reductase, 360 nmol/min per mg; malate dehydrogenase, 240 nmol/min per mg; and glyceraldehyde-3-phosphate dehydrogenase, 100 nmol/min per mg. The kinetic properties (apparent V(max) and K(M) values), pH optimum, temperature dependence of the rate, and specificity for electron acceptors/donors of the different oxidoreductases were examined. Pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase were shown to be two separate enzymes specific for factor 420 rather than for nicotinamide adenine dinucleotide (NAD), NADP, or ferredoxin as the electron acceptor. Both activities catalyzed the reduction of methyl viologen with the respective alpha-ketoacid and a coenzyme A-dependent exchange between the carboxyl group of the alpha-ketoacid and CO(2). The data indicate that the two enzymes are similar to pyruvate synthase and alpha-ketoglutarate synthase, respectively. Fumarate reductase was found in the soluble cell fraction. This enzyme activity coupled with reduced benzyl viologen as the electron donor, but reduced factor 420, NADH, or NADPH was not effective. The cells did not contain menaquinone, thus excluding this compound as the physiological electron donor for fumarate reduction. NAD was the preferred coenzyme for malate dehydrogenase, whereas NADP was preferred for glyceraldehyde-3-phosphate dehydrogenase. The organism also possessed a factor 420-dependent hydrogenase and a factor 420-linked NADP reductase. The involvement of the described oxidoreductases in cell carbon synthesis is discussed.
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PMID:Oxidoreductases involved in cell carbon synthesis of Methanobacterium thermoautotrophicum. 91 79

1. The effects of protein concentration and ionic strength on the adsorption of the individual glycolytic enzymes to F-actin and F-actin--trypomyosin--troponin have been studied. 2. Appreciable association was demonstrated under conditions of physiological ionic strength and high protein concentration, and tropomyosin--troponin established as an important and generalized component of these interactions. 3. Phosphofructokinase, aldolase, pyruvate kinase, lactate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase and glucose-6-phosphate isomerase were strongly bound under these conditions, while triosephosphate isomerase, phosphoglycerate kinase, phosphoglycerate mutase, enolase and hexokinase displayed less adsorption to the structural proteins. 4. The influence of a number of parameters on the adsorption phenomena was examined. Ca2+ and fructose 1,6-diphosphate increased the adsorption of aldolase, lactate dehydrogenase and pyruvate kinase, while decreasing the adsorption of the enzymes of the constant-proportion group. 5. Of the other major enzymic components of skeletal muscle, creatine kinase, adenylate kinase and malate dehydrogenase showed no adsorption to F-actin--tropomyosin--troponin under the experimental conditions. Some adsorption was evident, however, in the case of aspartate aminotransferase, (NADP) isocitrate dehydrogenase and alpha-glycerolphosphate dehydrogenase. 6. These results have been discussed in relation to their functional significance and the roles of enzyme compartmentation in the cell.
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PMID:On the association of glycolytic enzymes with structural proteins of skeletal muscle. 111 88

Homogenates of dark-pretreated leaves yield two particulate fractions in density gradient centrifugation: one contains chlorophyll (chloroplasts) while a second fraction contains ribulose-1, 5-bisphophate carboxylase, NADP-dependent glyceraldehyde-3-phosphate dehydrogenase and catalase. Addition of a microbody-rich pellet to chloroplasts isolated from dark-pretreated plants largely enhances both oxygen evolution and CO2-fixation into organic compounds. The pathway of CO2 reduction may be part of a membrane system which, under suitable conditions, may separate from the chloroplast as a distinct cytoplasmic entity, having physical properties similar to those of microbodies.
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PMID:Studies on the intracellular location of enzymes of the photosynthetic carbon-reduction cycle. 120 6

By combining our knowledge of the crystal structure of the glycolytic NAD-dependent glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the sequence of the photosynthetic NADP-dependent GAPDH of the chloroplast, two particular amino acid residues were predicted as the principal determinants of differing coenzyme specificity. By use of site-directed mutagenesis, the amino acids Leu 187 and Pro 188 of GAPDH from Bacillus stearothermophilus have been replaced with Ala 187 and Ser 188, which occur in the sequence from the chloroplast enzyme. The resulting mutant was shown to be catalytically active not only with its natural coenzyme NAD but also with NADP, thus confirming the initial hypothesis. This approach has not only enabled us to alter the coenzyme specificity by minimal amino acid changes but also revealed factors that control the relative affinity of the enzyme for NAD and NADP.
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PMID:Probing the coenzyme specificity of glyceraldehyde-3-phosphate dehydrogenases by site-directed mutagenesis. 222 64


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