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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)

Neutral salts enhanced the specific activity of chloroplast NADP-glyceraldehyde-3-phosphate dehydrogenase (D-glyceraldehyde-3-phosphate:NADP+ oxidoreductase (phosphorylating), EC 1.2.1.13) from spinach leaves. The ordering of the respective anions, according to the concentration for maximal stimulation, yielded the lyotropic (Hofmeister) series [SCN- (0.05 M), ClO-4 (0.08 M), Cl3CCO-2 (0.24 M), I- (0.35 M), Br- (0.6 M), Cl- (1.0 M)]; the more chaotropic the anion the less its concentration for maximal activation. Neither the NAD-linked activity of the chloroplast enzyme nor glyceraldehyde-3-phosphate dehydrogenases originating from cyanobacteria and rabbit muscle were stimulated by neutral salts. Chaotropic anions also enhanced the catalytic capacity of the chloroplast enzyme at concentrations lower than those required for the activation process. In the presence of 0.12 M NaBr the rate of catalysis was maximum whereas the highest conversion from the inactive to an active form was observed at 0.6 M NaBr. On the other hand, nonstimulatory concentrations of chaotropic anions lowered the concentration of ATP, Pi, and NADPH required for maximum stimulation of the specific activity (concerted hysteresis). On the basis that the enhancement of NADP-glyceraldehyde-3-phosphate dehydrogenase (and other chloroplast enzymes) by chaotropic anions paralleled the effect of organic solvents and reduced thioredoxin, it appeared that the modification of hydrophobic (intramolecular) interactions participates in the mechanism of light-mediated regulation.
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PMID:Modulation of spinach chloroplast NADP-glyceraldehyde-3-phosphate dehydrogenase by chaotropic anions. 233 56

The stereospecificity of the reaction catalysed by the spinach chloroplast enzyme NADP-dependent glyceraldehyde-3-phosphate dehydrogenase (D-glyceraldehyde-3-phosphate: NADP+ oxidoreductase (phosphorylating), EC 1.2.1.13) with respect to the C4 nicotinamide hydrogen transfer was investigated. NADPH deuterated at the C4 HA position was synthesized using aldehyde dehydrogenase. 1H-NMR spectroscopy was used to examine the NADP+ product of the GPDH reaction for the presence or absence of the C4 deuterium atom. Chloroplast NADP-dependent glyceraldehyde-3-phosphate dehydrogenase retains the deuterium at the C4 HA position (removing the hydrogen atom), and is therefore a B (pro-S) specific dehydrogenase.
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PMID:Stereospecificity of C4 nicotinamide hydrogen transfer of the NADP-dependent glyceraldehyde-3-phosphate dehydrogenase. 252 66

A Tris-citrate pH 9.5 gel/borate pH 8.2 electrode discontinuous buffer system for starch gel electrophoresis of proteins was developed to resolve iso- and allozymes of aspartate aminotransferase in frogs (Hyla crucifer). This buffer system also enhanced resolution of NADP-dependent malate dehydrogenase and the L-lactate dehydrogenase-A locus in this species. It provided good resolution of NAD-dependent malate dehydrogenase in esocid fishes, and esterases, glycerol-3-phosphate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, alcohol dehydrogenase, and S-aconitate hydratase in ambystomatid salamanders. Variation suppressed by other buffers was revealed by this buffer for some enzyme encoding loci, while at other loci, this buffer suppressed electromorph variability. The concentration of tris(hydroxymethyl)aminomethane in gels made with this buffer was much higher than in pH 8.7 "Poulik" gels, but running characteristics of the two gel types were similar. Gels made with this new buffer were less prone to splitting and "warping" than Poulik gels, and were easier to handle. When screening a given taxon for enzyme variability, tests using multiple buffers are essential to maximize the amount of electrophoretically detectable variation.
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PMID:A high pH discontinuous buffer system for resolution of isozymes in starch gel electrophoresis. 279 42

The specific activities of each of the enzymes of the classical pentose phosphate pathway have been determined in both cultured procyclic and bloodstream forms of Trypanosoma brucei. Both forms contained glucose-6-phosphate dehydrogenase (EC 1.1.1.49), 6-phosphogluconolactonase (EC 3.1.1.31), 6-phosphogluconate dehydrogenase (EC 1.1.1.44), ribose-5-phosphate isomerase (EC 5.3.1.6) and transaldolase (EC 2.2.1.2). However, ribulose-5-phosphate 3'-epimerase (EC 5.1.3.1) and transketolase (EC 2.2.1.1) activities were detectable only in procyclic forms. These results clearly demonstrate that both forms of T. brucei can metabolize glucose via the oxidative segment of the classical pentose phosphate pathway in order to produce D-ribose-5-phosphate for the synthesis of nucleic acids and reduced NADP for other synthetic reactions. However, only procyclic forms are capable of using the non-oxidative segment of the classical pentose phosphate pathway to cycle carbon between pentose and hexose phosphates in order to produce D-glyceraldehyde 3-phosphate as a net product of the pathway. Both forms lack the key gluconeogenic enzyme, fructose-bisphosphatase (EC 3.1.3.11). Consequently, neither form should be able to engage in gluconeogenesis nor should procyclic forms be able to return any of the glyceraldehyde 3-phosphate produced in the pentose phosphate pathway to glucose 6-phosphate. This last specific metabolic arrangement and the restriction of all but the terminal steps of glycolysis to the glycosome may be the observations required to explain the presence of distinct cytosolic and glycosomal isoenzymes of glyceraldehyde-3-phosphate dehydrogenase and phosphoglycerate kinase. These same observations also may provide the basis for explaining the presence of cytosolic hexokinase and phosphoglucose isomerase without the presence of any cytosolic phosphofructokinase activity. The key enzymes of the Entner-Doudoroff pathway, 6-phosphogluconate dehydratase (EC 4.2.1.12) and 2-keto-3-deoxy-6-phosphogluconate aldolase (EC 4.1.2.14) were not detected in either procyclic or bloodstream forms of T. brucei.
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PMID:The enzymes of the classical pentose phosphate pathway display differential activities in procyclic and bloodstream forms of Trypanosoma brucei. 292 7

Mutants of mucoid Pseudomonas aeruginosa defective in fructose-bisphosphate aldolase (FBA), NADP-linked glyceraldehyde-3-phosphate dehydrogenase (GAP) or 3-phosphoglycerate kinase (PGK) were unable to grow on gluconeogenic precursors like glutamate, succinate or lactate. The gap and pgk mutants could grow on glucose, gluconate or glycerol, but fba mutants could not. This suggests that the metabolism of glucose or gluconate does not require either PGK or NADP-linked GAP but does require the operation of the aldolase-catalysed step. For gluconeogenesis, however, all three steps are essential. Recombinant plasmids carrying genes for FBA, PGK, GAP or phospho-2-keto-3-deoxygluconate aldolase (EDA) activities were constructed from a genomic library of mucoid P. aeruginosa selecting for complementation of deficiency mutations. Analysis of their complementation profile indicated that one group of plasmids carried fba and pgk genes, while another group carried eda, 6-phosphogluconate dehydratase (edd) and glucose-6-phosphate dehydrogenase (zwf) genes. The gap gene was not linked to any of these markers. Partial restoration of FBA activity in spontaneous revertants of Fba- mutants was accompanied by a concomitant loss of PGK activity. These experiments indicate a linkage between the fba and pgk genes on the P. aeruginosa chromosome.
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PMID:Gluconeogenic mutations in Pseudomonas aeruginosa: genetic linkage between fructose-bisphosphate aldolase and phosphoglycerate kinase. 311 66

Both NAD- and NADP-dependent glyceraldehyde-3-phosphate dehydrogenase (G3PDH) (EC 1.2.1.12) activities were detected in glucose-grown cells of Pseudomonas aeruginosa strain PAO. After growth on gluconeogenic substrates such as citrate, the activity of the NAD-G3PDH was reduced severalfold in contrast to little change for the NADP-G3PDH. The two G3PDH activities could be separated by ammonium sulphate fractionation. PAGE revealed the presence of two G3PDH isoenzymes of 140 (NADP-specific) and 315 (NAD-specific) kDa. Slight differences were observed in the thermostabilities and pH optima of the two enzymes whereas the regulation of their activities by various compounds varied strongly. The NADP-G3PDH enzyme was activated by ATP, reduced NAD, and fructose 6-phosphate. It was inhibited by fructose 1,6-diphosphate and 6-phosphogluconate. The NAD-G3PDH enzyme was inhibited by ATP, reduced NAD, and 6-phosphogluconate; it was slightly activated by reduced NADP. The possible roles of these isoenzymes in the control of hexose catabolism and gluconeogenesis in P. aeruginosa are discussed.
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PMID:Multiple enzyme forms of glyceraldehyde-3-phosphate dehydrogenase in Pseudomonas aeruginosa PAO. 312 38

NADP-dependent nonphosphorylating D-glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.9) from spinach leaves has been purified to apparent electrophoretic homogeneity by ammonium sulfate fractionation, molecular sieving on Sephadex G-200, DEAE-cellulose, and 2',5'-ADP-Sepharose affinity chromatography. The purified enzyme exhibited a specific activity of 15 mumol (mg protein)-1 min-1 and was characterized as a homotetramer with a native molecular weight of 195,000. Preincubation of the purified enzyme with NADP+ resulted in an almost twofold increase in enzymatic activity. The rate of activation was slower than the rate of catalysis, indicating that the enzyme has hysteretic properties. This behavior results in a lag phase during activity measurement of the enzyme preincubated without NADP+. Substrate interaction and product inhibition studies suggest a rapid equilibrium random BiBi mechanism for the reaction. Thiol modifying reagents, iodoacetamide and diamide, completely inactivated the purified enzyme. Inactivation by iodoacetamide exhibited pseudo-first-order kinetics with a rate constant of 0.17 min-1. D-Glyceraldehyde 3-phosphate effectively protected the enzyme against inactivation by thiol reagents, suggesting that modification occurred at or near the substrate-binding site. Complete inactivation of the dehydrogenase was correlated with incorporation of 8 mol [1-14C]iodoacetamide/mol enzyme. Total protection afforded by D-glyceraldehyde 3-phosphate against enzyme inactivation by iodoacetamide was correlated with a protection of 4 mol reactive residues/mol enzyme. On the basis of these results it is suggested that one sulfhydryl group per enzyme subunit is essential for catalysis in spinach leaf nonphosphorylating glyceraldehyde-3-phosphate dehydrogenase. A kinetic and molecular mechanism for the reaction is proposed.
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PMID:Purification and kinetic and structural properties of spinach leaf NADP-dependent nonphosphorylating glyceraldehyde-3-phosphate dehydrogenase. 334 66

Kinetic analysis of glyceraldehyde-3-phosphate dehydrogenase showed that the enhancement of the NADP-linked activity by specific chloroplast modulators is a concerted process; either a selected second metabolite or the couple dithiothreitol/thioredoxin-f lowers the concentration of primary modulators (ATP, NADPH, inorganic phosphate, 1,3-diphosphoglycerate) required for maximal stimulation (A0.5). Organic solvents also stimulate NADP-glyceraldehyde-3-phosphate dehydrogenase in the absence of any modulator; the concentration for the highest specific activity correlates inversely with the respective octanol-water partition coefficient. On the other hand, alcohols also enhance enzyme activity by lowering the A0.5 for primary modulators. Another compound--spermine--inhibits both the ATP- and the inorganic phosphate-mediated activation, but it does not influence the NADPH-induced process.
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PMID:Activation of spinach chloroplast NADP-linked glyceraldehyde-3-phosphate dehydrogenase by concerted hysteresis. 396 15

The redox status of three biological components capable of undergoing oxidation-reduction reactions, glutathione, NAD and NADP, were determined in muscle tissues of young and old rats. A considerable increase in the relative concentration of the oxidized form, at the expense of the reduced one was found in the old tissue reflecting a significantly less reducing environment than in young cells. The effects of varying the ratio of reduced/oxidized glutathione in vitro on the activity of the enzyme glyceraldehyde-3-phosphate dehydrogenase extracted from young and old animals were compared. It was found that concentrations of GSSG as found in old muscle tissue do not affect enzyme samples extracted from young muscle. The accumulation of oxidized glutathione observed in old cells does not, therefore, directly cause the age-related activity loss of this enzyme.
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PMID:Age-related changes in the redox status of rat muscle cells and their role in enzyme-aging. 398 83

Photosynthetic GAPDH has been studied in chloroplast extracts, obtained in presence of physiological concentrations of NADP and NAD. The enzyme is shown to have a molecular weight of 600,000, on the basis of zymograms obtained after electrophoresis on polyacrylamide gradient gels. Km values of 0.08 and 0.16 mM, respectively, were found for NADP and NAD. The same V is reached with both NADP and NAD. The two coenzymes bind to the enzyme at the same catalytic site.
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PMID:Conformation and kinetic properties of photosynthetic glyceraldehyde-3-phosphate dehydrogenase "in vivo". 708 38


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