Gene/Protein Disease Symptom Drug Enzyme Compound
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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)

Human erythrocytes from healthy male donors were fractionated with respect to in vivo age by simple centrifugation in order to characterize changes in the functional integrity of the membrane during the life-span of the cell. The three enzymes, Na/K-ATPase, glyceraldehyde-3-phosphate dehydrogenase and NADH-ferricyanide reductase, were found not to change with age, but significant age-dependent decreases were observed in the cases of acetylcholinesterase, phosphoglycerate kinase, purine nucleoside phosphorylase, adenylate kinase, Mg-ATPase and alkaline phosphatase. The possibility that these changes were attributable to mechanisms other than age-related inactivation, such as reticulocyte contamination, differential resealing and crypticity, was investigated. Only the decrease in acetylcholinesterase could be explained wholly in terms of reticulocyte contamination. A decrease in membrane integrity on ageing was observed, which accounted for approximately half the change in alkaline phosphatase and may have contributed to the other enzyme activity changes. This membrane integrity effect masked a real decrease in the highly cryptic NADH-ferricyanide reductase, this decrease being apparent only after total disaggregation of the membrane with nonionic surfactant.
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PMID:Changes in the activities of some membrane-associated enzymes during in vivo ageing of the normal human erythrocyte. 14 40

A variety of phosphonates (XPO32-; X = H-, CH3-, CL3C-, CH3CH2-, and phenyl-) as well as methylarsonate have been shown to be suitable phosphate analogs for the reactions catalyzed by yeast glyceraldehyde-3-phosphate dehydrogenase and calf spleen purine nucleoside phosphorylase. The reactivity of the phosphate analogs with these two enzymes is independent of the pKa of the analog.
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PMID:Enzymic reactions of phosphate analogs. 40 43

Phenotypes of eight red cell enzymes at nine genetic loci were determined in the semi-free-ranging population of rhesus macaques; Macaca mulatta, that inhabit Cayo Santiago. The following enzymes were examined electrophoretically: adenosine deaminase, glucose-6-phosphate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, indophenol oxidase, lactate dehydrogenase, malate dehydrogenase, phosphoglucomutase-1, phosphoglumutase-2, and purine nucleoside phosphorylase. Hemolysates from at least 372 animals were analyzed, and no variants of the enzymes were observed with the exception of malate dehydrogenase. Three animals displaying a variant form of malate dehydrogenase were found.
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PMID:Genetic studies of free-ranging macaques of Cayo Santiago. I. Description of the population and some nonpolymorphic red cell enzymes. 41 22

A summary of a survey of three genera of mycoplasmatales (Mycoplasma, Acholeplasma, and Ureaplasma) for isozyme expression is presented. Isozyme analysis of mycoplasmas has been employed in at least three distinct areas: (1) as genetic markers for identification, individualization, and taxonomic classification; (2) as markers for cell culture contamination; and (3) as a qualitative measure of the operative metabolic pathways in the diverse species. We have found five ubiquitous enzymes: purine nucleoside phosphorylase, adenylate kinase, inorganic pyrophosphatase, dipeptidase, and esterase. Three enzymes, glucose-6-phosphate dehydrogenase, phosphogluconate dehydrogenase, and superoxide dismutase, were restricted to Acholeplasma species and were not detected in Mycoplasma or Ureaplasma. Four glycolytic enzymes, glucose phosphate isomerase, triose phosphate isomerase, glyceraldehyde-3-phosphate dehydrogenase, and lactate dehydrogenase, were restricted to those species of Mycoplasma and Acholeplasma capable of glucose fermentation. Two of these glycolytic enzymes, glucose phosphate isomerase and lactate dehydrogenase, were detected in serovars I and II of U. urealyticum, which is inconsistent with the non-glycolytic activity in this genus.
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PMID:On the distribution and characteristics of isozyme expression in Mycoplasma, Acholeplasma, and Ureaplasma species. 667 51

Crude extracts of triple-cloned, purified cultures of 22 species of Mycoplasma and Acholeplasma were examined for expression of 21 isozyme systems routinely used to type mammalian cells. Nine previously described enzymes (purine nucleoside phosphorylase, adenylate kinase, dipeptidase, esterase, glyceraldehyde-3-phosphate dehydrogenase, glucose phosphate isomerase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and superoxide dismutase) and three enzymes not previously reported in mycoplasma (triose phosphate isomerase, inorganic pyrophosphatase, and acid phosphatase) were detected in some or all of the species examined. These findings provide new information on the enzymatic expressions of these organisms. Three of the isozyme systems (superoxide dismutase, glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase) were present in Acholeplasma species but not in any Mycoplasma species. The characteristic pattern of electrophoretic mobility of the 12 isozyme systems also provides a useful biochemical property for identification, characterization, and classification of these mycoplasmas. Mycoplasma isozyme expression for seven of the enzymes were readily detected in various infected-cell culture lines by using either cell extracts or concentrated cell culture fluids. Mycoplasma-specific enzymes found in infected-cell extracts had the same electrophoretic mobility patterns as enzymes obtained from broth-grown mycoplasmas of the same species. Expression of homologous mammalian enzymes was not detectably altered by infection with mycoplasmas.
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PMID:Analysis of multiple isoenzyme expression among twenty-two species of Mycoplasma and Acholeplasma. 721 1

Arsenate (As(V)) is reduced in the body to the more toxic arsenite (As(III)). We have shown that two enzymes catalyzing phosphorolytic cleavage of their substrates, namely purine nucleoside phosphorylase and glyceraldehyde-3-phosphate dehydrogenase, can reduce As(V) in presence of an appropriate thiol and their substrates. Another phosphorolytic enzyme that may also reduce As(V) is glycogen phosphorylase (GP). With inorganic phosphate (P(i)), GP catalyzes the breakdown of glycogen to glucose-1-phosphate; however, it also accepts As(V). Testing the hypothesis that GP can reduce As(V), we incubated As(V) with the phosphorylated GPa or the dephosphorylated GPb purified from rabbit muscle and quantified the As(III) formed from As(V) by high-performance liquid chromatography-hydride generation-atomic fluorescence spectrometry. In the presence of adenosine monophosphate (AMP), glycogen, and glutathione (GSH), both GP forms reduced As(V) at rates increasing with enzyme and As(V) concentrations. The As(V) reductase activity of GPa was 10-fold higher than that of GPb. However, incubating GPb with GP kinase and ATP (that converts GPb to GPa) increased As(V) reduction by phosphorylase up to the rate produced by GPa incubated under the same conditions. High concentration of inorganic sulfate, which activates GPb like phosphorylation, also promoted reduction of As(V) by GPb. As(V) reduction by GPa (like As(V) reduction in rats) required GSH. It also required glycogen (substrate for GP) and was stimulated by AMP (allosteric activator of GP) even at low micromolar concentrations. P(i), substrate for GP competing with As(V), inhibited As(III) formation moderately at physiological concentrations. Glucose-1-phosphate, the product of GP-catalyzed glycogenolysis, also decreased As(V) reduction. Summarizing, GP is the third phosphorolytic enzyme identified capable of reducing As(V) in vitro. For reducing As(V) by GP, GSH and glycogen are indispensable, suggesting that the reduction is linked to glycogenolysis. While its in vivo significance remains to be tested, further characterization of the GP-catalyzed As(V) reduction is presented in the adjoining paper.
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PMID:Glutathione-dependent reduction of arsenate by glycogen phosphorylase a reaction coupled to glycogenolysis. 1769 25

Three cytosolic phosphorolytic/arsenolytic enzymes, (purine nucleoside phosphorylase [PNP], glycogen phosphorylase, glyceraldehyde-3-phosphate dehydrogenase) have been shown to mediate reduction of arsenate (AsV) to the more toxic arsenite (AsIII) in a thiol-dependent manner. With unknown mechanism, hepatic mitochondria also reduce AsV. Mitochondria possess ornithine carbamoyl transferase (OCT), which catalyzes phosphorolytic or arsenolytic citrulline cleavage; therefore, we examined if mitochondrial OCT facilitated AsV reduction in presence of glutathione. Isolated rat liver mitochondria were incubated with AsV, and AsIII formed was quantified. Glutathione-supplemented permeabilized or solubilized mitochondria reduced AsV. Citrulline (substrate for OCT-catalyzed arsenolysis) increased AsV reduction. The citrulline-stimulated AsV reduction was abolished by ornithine (OCT substrate inhibiting citrulline cleavage), phosphate (OCT substrate competing with AsV), and the OCT inhibitor norvaline or PALO, indicating that AsV reduction is coupled to OCT-catalyzed arsenolysis of citrulline. Corroborating this conclusion, purified bacterial OCT mediated AsV reduction in presence of citrulline and glutathione with similar responsiveness to these agents. In contrast, AsIII formation by intact mitochondria was unaffected by PALO and slightly stimulated by citrulline, ornithine, and norvaline, suggesting minimal role for OCT in AsV reduction in intact mitochondria. In addition to OCT, mitochondrial PNP can also mediate AsIII formation; however, its role in AsV reduction appears severely limited by purine nucleoside supply. Collectively, mitochondrial and bacterial OCT promote glutathione-dependent AsV reduction with coupled arsenolysis of citrulline, supporting the hypothesis that AsV reduction is mediated by phosphorolytic/arsenolytic enzymes. Nevertheless, because citrulline cleavage is disfavored physiologically, OCT may have little role in AsV reduction in vivo.
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PMID:Glutathione-supported arsenate reduction coupled to arsenolysis catalyzed by ornithine carbamoyl transferase. 1924 96

Several mammalian enzymes catalyzing the phosphorolytic-arsenolytic cleavage of their substrates (thus yielding arsenylated metabolites) have been shown to facilitate reduction of arsenate (AsV) to the more toxic arsenite (AsIII) in presence of their substrate and a thiol. These include purine nucleoside phosphorylase (PNP), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and glycogen phosphorylase-a (GPa). In this work, we tested further enzymes, the bacterial phosphotransacetylases (PTAs) and PNP, for AsV reduction. The PTAs, which arsenolytically cleave acetyl-CoA producing acetyl-arsenate, were compared with GAPDH, which can also form acetyl-arsenate by arsenolysis of its nonphysiological substrate, acetyl-phosphate. As these enzymes also mediated AsV reduction, we can assert that facilitation of thiol-dependent AsV reduction may be a general property of enzymes that catalyze phosphorolytic-arsenolytic reactions. Because with all such enzymes arsenolysis is obligatory for AsV reduction, we analyzed the relationship between these two processes in presence of various thiol compounds, using PNP. Although no thiol influenced the rate of PNP-catalyzed arsenolysis, all enhanced the PNP-mediated AsV reduction, albeit differentially. Furthermore, the relative capacity of thiols to support AsV reduction mediated by PNP, GPa, PTA, and GAPDH apparently depended on the type of arsenylated metabolites (i.e., arsenate ester or anhydride) produced by these enzymes. Importantly, AsV reduction by both acetyl-arsenate-producing enzymes (i.e., PTA and GAPDH) exhibited striking similarities in responsiveness to various thiols, thus highlighting the role of arsenylated metabolite formation. This observation, together with the finding that PNP-mediated AsV reduction lags behind the PNP-catalyzed arsenolysis lead to the hypothesis that arsenolytic enzymes promote reduction of AsV by forming arsenylated metabolites which are more reducible to AsIII by thiols than inorganic AsV. This hypothesis is evaluated in the adjoining paper.
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PMID:Mechanism of thiol-supported arsenate reduction mediated by phosphorolytic-arsenolytic enzymes: I. The role of arsenolysis. 1947 19

Enzymes catalyzing the phosphorolytic cleavage of their substrates can reduce arsenate (AsV) to the more toxic arsenite (AsIII) via the arsenolytic substrate cleavage in presence of a reductant, as glutathione or dithiotreitol (DTT). We have shown this for purine nucleoside phosphorylase (PNP), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), glycogen phosphorylase-a (GPa), and phosphotransacetylase (PTA). Using a multidisciplinary approach, we explored the mechanism whereby these enzymes mediate AsV reduction. It is known that PNP cleaves inosine with AsV into hypoxanthine and ribose-1-arsenate. In presence of inosine, AsV and DTT, PNP mediates AsIII formation. In this study, we incubated PNP first with inosine and AsV, allowing the arsenolytic reaction to run, then blocked this reaction with the PNP inhibitor BCX-1777, added DTT and continued the incubation. Despite inhibition of PNP, large amount of AsIII was formed in these incubations, indicating that PNP does not reduce AsV directly but forms a product (i.e., ribose-1-arsenate) that is reduced to AsIII by DTT. Similar studies with the other arsenolytic enzymes (GPa, GAPDH, and PTA) yielded similar results. Various thiols that differentially supported AsV reduction when present during PNP-catalyzed arsenolysis (DTT approximately dimercaptopropane-1-sulfonic acid > mercaptoethanol > DMSA > GSH) similarly supported AsV reduction when added only after a transient PNP-catalyzed arsenolysis, which preformed ribose-1-arsenate. Experiments with progressively delayed addition of DTT after BCX-1777 indicated that ribose-1-arsenate is short-lived with a half-life of 4 min. In conclusion, phosphorolytic enzymes, such as PNP, GAPDH, GPa, and PTA, promote thiol-dependent AsV reduction because they convert AsV into arsenylated products reducible by thiols more readily than AsV. In support of this view, reactivity studies using conceptual density functional theory reactivity descriptors (local softness, nucleofugality) indicate that reduction by thiols of the arsenylated metabolites is favored over AsV.
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PMID:Mechanism of thiol-supported arsenate reduction mediated by phosphorolytic-arsenolytic enzymes: II. Enzymatic formation of arsenylated products susceptible for reduction to arsenite by thiols. 1947 37