Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

It is shown that the modulation in the negative cooperativity of ligand binding by another, competing ligand that binds noncooperatively is accounted for exclusively by the ligand-induced sequential model. It is therefore suggested that whenever such a phenomenon is observed it argues strongly in favor of the sequential model. The advantages and limitations of this approach are evaluated. The binding of the coenzymes NAD+ and nicotinamide-1-N6-ethenoadenine dinucleotide to rabbit muscle apo-glyceraldehyde-3-phosphate dehydrogenase [D-glyceraldehyde-3-phosphate:NAD+ oxidoreductase (phosphorylating; EC 1.2.1.12] exhibits strong negative cooperativity, whereas acetylpyridine adenine dinucleotide, ATP, and ADP-ribose bind noncooperatively to the NAD+ sites. The strong abolished in the presence of acetylpyridine adenine dinucleotide and strongly weakened by ATP, ADP, and AMP, but was not affected by addition of ADP-ribose. These findings demonstrate that the negative cooperativity in coenzyme binding to this enzyme results from sequential conformational changes and exclude the pre-existent asymmetry model as a possible explanation. These results also support the view that the structure of the pyridine moiety of the coenzyme analogs plays a role in orienting the adenine moiety at the adenine subsite, therefore affecting the cooperativity in the binding of the coenzyme analog which is mediated through the adenine subsites.
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PMID:Mechanism of negative cooperativity in glyceraldehyde-3-phosphate dehydrogenase deduced from ligand competition experiments. 693 45

The cytosolic phosphate potential was estimated in isolated rat liver parenchymal cells incubated with various gluconeogenic substrates. The value of the cytosolic [ATP]/[ADP][Pi] ratio was either estimated directly from measurements of ATP, ADP and Pi after digitonin fractionation of the cells, or calculated by the metabolite indicator method. When cells were incubated with lactate, pyruvate or alanine so that net flux through the indicator enzymes was in gluconeogenic direction, there was excellent agreement between the values obtained by the two methods over a wide range of fluxes. However, when the cells were incubated with substrates that could be converted both to glucose and to lactate so that net flux through the indicator enzymes was in the glycolytic direction, a large difference in the values of the cytosolic [ATP]/([ATP][Pi]) ratio as derived by the two methods was observed. It is concluded that the reaction catalyzed by glyceraldehyde-3-phosphate dehydrogenase plus 3-phosphoglycerate kinase is out of equilibrium when flux through the reaction is the glycolytic direction, and that use of the metabolite indicator method for the calculation of the cytosolic phosphate potential under these conditions leads to erroneous values.
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PMID:An evaluation of the metabolite indicator method for determining the cytosolic phosphate potential in rat liver cells. 713 15

Regulation of glucose metabolism in glycolysis by round spermatids was studied. Assay of activities of 11 glycolytic enzymes in cell-free spermatid extracts showed that hexokinase, phosphofructokinase, and glyceraldehyde-3-phosphate dehydrogenase had the lowest activities. When the cells were incubated with glucose (10 mM), the intracellular level of ATP fell rapidly and 5'-AMP increased. The ADP level remained unchanged. During incubation with glucose, fructose-1,6-bisphosphate, dihydroxyacetone phosphate, and glyceraldehyde-3-phosphate were accumulated without any change in a mass action ratio of fructose bisphosphate aldolase. Glyceraldehyde-3-phosphate dehydrogenase appeared to play a regulatory role in glycolysis. Glyceraldehyde-3-phosphate dehydrogenase was inhibited by the following compounds (Ki values in parentheses): adenosine (4.34 mM), 5'-AMP (3.50 mM), ADP (2.35 mM), ATP (5.34 mM), and 3',5'-cAMP (0.60 mM). In each case, the inhibition was competitive with NAD (Km = 0.20 mM). The 2'-hydroxy group of the adenine-linked ribose moiety was essential for binding. The compounds adenine, 2'-deoxyadenosine, 2'-AMP, 3'-AMP, CTP, GTP, UTP, and NADP showed little inhibition. These findings suggest that regulation of glycolysis in round spermatids by glyceraldehyde-3-phosphate dehydrogenase is most likely and that glyceraldehyde-3-phosphate dehydrogenase is inhibited by the adenine nucleotides, particularly by 5'-AMP and ADP as inhibitors competitive with NAD.
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PMID:Regulation of glucose metabolism by adenine nucleotides in round spermatids from rat testes. 714 87

1. Intracellular K increases the ouabain-sensitive Na-K exchange in human red blood cells. Pump rate increases hyperbolically with internal K with a K12 for K of 2.58 m-mole/l. red blood cells. Li also stimulates the pump rate, but with a much higher K12. The stimulation does not result from a change in the affinity of the pump for its substrates Na, K or Mg or for the product, phosphate. 2. The effect of cell K on the Na-Na exchange is biphasic. At low concentrations it decreases the exchange rate but then the exchange increases linearly with cell k concentration. 3. Stimulation of the pump rate by internal K can be demonstrated in reconstituted ghosts but only if the ratio of the volume of cells to that of solution at the time of haemolysis is high. Stimulation is not observed if the ghosts contain an efficient system for rephosphorylating ADP to ATP, such as creatine phosphate and creatine kinase, or if the measurements are made with iodoacetamide which inhibits rephosphorylation of ADP by inhibiting the enzyme glyceraldehyde-3-phosphate dehydrogenase. 4. Cells with low internal K and Li have low ATP concentrations, and ATP increases hyperbolically with internal K or Li with the same K12 as does the pump rate. In cells depleted of substrate intracellular K does not stimulate the pump rate. 5. The effect of K and Li on the pump rate probably does not result from enhanced activity of any of the enzymes below phosphofructokinase in the glycolytic pathway.
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PMID:Internal potassium stimulates the sodium-potassium pump by increasing cell ATP concentration. 732 Sep 24

The binding of nicotinamide--adenine dinucleotide (NAD+), nicotinamide--1,N6-ethenoadenine dinucleotide (epsilon NAD+), acetylpyridine--adenine dinucleotide (AcPyAD+), ATP, and adenosine diphosphoribose (ADP-ribose) to rabbit muscle glyceraldehyde-3-phosphate dehydrogenase (the enzyme) was examined. NAD+ and epsilon NAD+ were found to bind to the apoenzyme in a negatively cooperative manner, whereas AcPyAD+, ATP, and ADP-ribose bind non-cooperatively to the NAD+ sites. The strong negative cooperativity in coenzyme binding was found to be abolished in the presence of AcPyAD+ and strongly weakened by ATP, ADP, and AMP, but was not affected by the addition of ADP-ribose. These findings demonstrate that the mechanism of the negative cooperativity in coenzyme binding to the enzyme involves ligand-induced conformational changes between neighboring sites. These findings cannot be accounted for by the pre-existent asymmetry model. The results support our previous hypothesis that the structure of the pyridine moiety of the coenzyme analogues plays a role in orienting the adenine moiety in the adenine subsite, and thus affects the cooperativity observed in the binding of the coenzyme analogue.
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PMID:The sequential nature of the negative cooperativity in rabbit muscle glyceraldehyde-3-phosphate dehydrogenase. 744 64

Nitric oxide signaling is achieved through cGMP-dependent and -independent mechanisms. The latter are exemplified by the NAD(+)-dependent automodification of the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The experimental post-translational, covalent modification of the enzyme by [32P]NAD+ is achieved using NO-releasing compounds and an active constitutive or inducible NO-synthase. Potential roles for NO in this covalent enzyme modification can be grouped as follows: S-Nitrosylation of GAPDH by NO+ NAD(+)-dependent, post-translational covalent automodification of GAPDH. Oxidative modification of GAPDH by NO-related compounds, probably ONOO. GAPDH modification by one of the proposed mechanisms would lead to inhibition of enzyme catalysis. It is likely that the NAD(+)-dependent automodification process occurs in vitro, in intact cells, and in whole animals. Besides its normal function in glycolysis, GAPDH not only is a target for NO-mediated direct and indirect modifications but also is ADP-ribosylated in the presence of brefeldin A (90). The relation of such ADP-ribosylation to enzyme activity is so far unknown. GAPDH also may be involved in one of the following functions unrelated to its glycolytic activity (81 and refs. therein; 90): binding and transport of tRNA associated with nuclear localization of GAPDH. DNA-repair activity, i.e., uracil DNA glycosylase. Activation of transcription in neurons. Interaction with tubulin and microtubules. The transport of nitric oxide. Serves as a substrate for brefeldin A stimulated ADP-ribosylation. Because some of these alternative functions of GAPDH, just like NO-mediated modification of the enzyme, are related to the NAD+ binding site of the protein, we are interested in searching for the significance of these activities in relation to NO actions. In recent years, several functions of NO have been linked to direct, cGMP-independent actions. Modification of GAPDH is probably just one interesting target related to NO-redox chemistry and active-site thiol modification. It will be challenging to investigate NO biochemistry in closer detail and to elucidate how NO targets biological systems, especially in relation to the patho-physiological role of NO in medically related conditions.
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PMID:Protein thiol modification of glyceraldehyde-3-phosphate dehydrogenase as a target for nitric oxide signaling. 754 26

Nitric oxide (NO), produced by vascular endothelial cells, mediates both physiological and pathological responses. Although the molecular targets responsible for NO-mediated endothelial cell injury are not known, one candidate is the glycolytic enzyme, glyceraldehyde-3-phosphate dehydrogenase (GAPDH). In this study, we investigated the mechanism involved in NO-mediated GAPDH inhibition and found that S-nitrosoglutathione (GSNO) inhibited GAPDH activity in both purified enzyme preparations and endothelial cells. Furthermore, GSNO-mediated GAPDH inhibition occurred by modification of the active site cysteine residue in GAPDH, since increasing concentrations of the substrate, glyceraldehyde-3-phosphate, which interacts with the active site cysteine residue, protected GAPDH from inhibition by GSNO. Although under certain conditions both GSNO and the NO donor, sodium nitroprusside (SNP), led to the covalent NAD(+)-dependent modification of GAPDH, this putative ADP ribosylation was unlikely to be the primary mechanism for inhibition, since the stoichiometry was extremely low, and, in the case of GSNO, inhibition was completely reversed by thiol reagents. Furthermore, GSNO effectively S-nitrosylated GAPDH, and the extent of nitrosylation was linearly correlated with the degree of inhibition such that addition of 1 mole of NO per mole of GAPDH monomer was necessary to inhibit the enzyme. Consistent with this finding, GSNO-mediated GAPDH inhibition was reversible with low-molecular-weight thiols, and the reversal of inhibition correlated with the "denitrosylation" of GAPDH. These results suggest that endothelial GAPDH is a target for NO and that inhibition occurs principally by the reversible S-nitrosylation of the active site cysteine residue in GAPDH.
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PMID:S-nitrosoglutathione reversibly inhibits GAPDH by S-nitrosylation. 757 5

Brefeldin A, a fungal metabolite that inhibits membrane transport, induces the mono(ADP-ribosyl)ation of two cytosolic proteins of 38 and 50 kDa as judged by SDS/PAGE. The 38-kDa substrate has been previously identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). We report that the 50-kDa BFA-induced ADP-ribosylated substrate (BARS-50) has native forms of 170 and 130 kDa, as determined by gel filtration of rat brain cytosol, indicating that BARS-50 might exist as a multimeric complex. BARS-50 can bind GTP, as indicated by blot-overlay studies with [alpha-32P]GTP and by photoaffinity labeling with guanosine 5'-[gamma-32P] [beta,gamma-(4-azidoanilido)]triphosphate. Moreover, ADP-ribosylation of BARS-50 was completely inhibited by the beta gamma subunit complex of G proteins, while the ADP-ribosylation of GAPDH was unmodified, indicating that this effect was due to an interaction of the beta gamma complex with BARS-50, rather than with the ADP-ribosylating enzyme. Two-dimensional gel electrophoresis and immunoblot analysis shows that BARS-50 is a group of closely related proteins that appear to be different from all the known GTP-binding proteins.
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PMID:Evidence that the 50-kDa substrate of brefeldin A-dependent ADP-ribosylation binds GTP and is modulated by the G-protein beta gamma subunit complex. 762 70

Nitric oxide (NO) induces a covalent modification of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from various tissues. This phenomenon, which has previously been interpreted as an auto-ADP-ribosylation, is in fact a covalent binding of NAD+ to the enzyme. In the present study, we show that 3-morpholino-sydnonimine (SIN-1) is much more efficient than sodium nitroprusside (SNP) in stimulating the covalent labelling of GAPDH from cultured striatal neurones in the presence of [adenylate-32P]NAD+ (877 +/- 110 and 266 +/- 33% increase in NAD(+)-labelling induced by maximally effective concentrations of SIN-1 and SNP respectively). The difference in the efficacy of both NO-generating compounds could be due to the additional release of superoxide by SIN-1, since superoxide dismutase and the nitrone 5,5'-dimethyl pyrroline-1-oxide markedly inhibited the SIN-1-induced covalent binding of NAD+ to GAPDH. Catalase and selective scavengers of hydroxyl radicals, mannitol and dimethyl sulphoxide, did not alter the SIN-1-induced covalent modification of GAPDH, ruling out the involvement of hydroxyl radicals in this phenomenon. Supporting further a role of oxygen free radicals in the NAD+ linkage to GAPDH, pyrogallol, a superoxide generator, which alone was ineffective, potentiated the SNP-evoked response. The NAD+ linkage to neuronal GAPDH measured in the presence of NO and superoxide probably involves sulphydryl groups, since the radiolabelling of the protein was reversed by exposure to HgCl2 and prevented by pretreatment with the alkylating agent N-ethylmaleimide. Moreover, the NO-induced inhibition of GAPDH activity was enhanced by pyrogallol, which was ineffective alone. In conclusion, the present study indicates that superoxide anions potentiate NO-induced covalent NAD(+)-linkage to GAPDH and enzyme inactivation.
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PMID:Oxygen free radicals enhance the nitric oxide-induced covalent NAD(+)-linkage to neuronal glyceraldehyde-3-phosphate dehydrogenase. 763 7

Impairment of energy metabolism was studied in jaundiced rabbit liver by kinetic analysis of energy transfer function. Free cytosolic ADP (ADPf), as calculated from the measured components of the glyceraldehyde-3-phosphate dehydrogenase and 3-phosphoglycerate kinase/lactate dehydrogenase reactions, decreased from the control value of 48.1 to 37.0 microM at 24 h after bile duct ligation. The maximal velocity (Vmax) of ATP synthesis, as measured by state 3 respiration of isolated mitochondria, decreased from the control value of 62.1 to 38.3 nmol ATP synthesized per min per mg mitochondrial protein, while the Michaelis constant for ADP (Km) decreased from the control value of 19.2 to 12.8 microM. ATP synthesis velocity in vivo }v: Vmax/[1 + (Km/[ADPf])], as calculated by Vmax, Km and ADPf, decreased from the control value of 44.4 to 28.5 nmol ATP synthesized per min per mg mitochondrial protein. Delta v/delta ADPf(delta v/delta ADPf: Vmax.Km/(Km + [ADPf])2), which indicates work-cost performance of the liver, decreased from the control value of 0.263 to 0.198. Biochemical output of the liver, as measured by hippurate synthesis from benzoate, decreased from the control value of 98.4 to 32.7 mg/h. These results indicate that synergistic decreases in ADPf, Vmax, v and delta v/delta ADPf take place in the course of deterioration of mitochondrial ATP synthesis and work output in jaundiced liver.
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PMID:Kinetic analysis of impaired work-cost performance in jaundiced rabbit liver. 765 37


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