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)

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

Glyceraldehyde-phosphate dehydrogenase (D-glyceraldehyde-3-phosphate : NADP+ oxidoreductase (phosphorylating), EC 1.2.1.13) from spinach chloroplasts is a polymeric protein of approx. 600,000 daltons and sodium dodecyl sulphate gel electrophoresis shows that it consists of two subunits of molecular weight 43,000 and 37,000. Comparison of amino acid analyses and tryptic peptide maps indicates that the two subunits have a different primary structure. The native enzyme contains 0.5 mol of NADP+ and 0.5 mol of NAD+ per protomer of 80,000 daltons, no reduced pyridine nucleotides have been detected. Almost complete inactivation is obtained by reaction of two cysteinyl residues per 80,000 daltons with tetrathionate or iodo[14C2]acetic acid; since the same amount of radioactivity is incorporated in the two subunits it is likely that they are both essential for the catalytic activity. Charcoal stripping of native glyceraldehyde-phosphate dehydrogenase produces an apoprotein which still retains most of the enzymatic activity but, unlike the holoenzyme, is gradually inactivated by storage at 4 degrees C and does not react with iodoacetate under the same conditions in which the holoenzyme is completely inactivated.
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PMID:Subunit structure and activity of glyceraldehyde-3-phosphate dehydrogenase from spinach chloroplasts. 2 61

Inactivation of apo-glyceraldehyde-3-phosphate dehydrogenase from rat skeletal muscle in the presence of butanedione is the result of modification of one arginyl residue per subunit of the tetrameric enzyme molecule. The loss of activity follows pseudo-first-order kinetics. NAD+ increases the apparent first-order rate constant of inactivation. The effect of NAD+ on the enzyme inactivation is cooperative (Hill coefficient = 2.3--3.2). Glyceraldehyde 3-phosphate protected the holoenzyme against inactivation, decreasing the rate constant of the reaction. At saturating concentrations of substrate the protection was complete. The Hill plot demonstrates that the effect is cooperative. This suggests that subunit interactions in the tetrameric holoenzyme molecule may affect the reactivity of the essential arginyl residues. In contrast, glyceraldehyde 3-phosphate had no effect on the rate of inactivation of the apoenzyme in the presence of butanedione. 100 mM inorganic phosphate protected both the apoenzyme and holoenzyme against inactivation. The involvement of the microenvironment of the arginyl residues in the functionally important conformational changes of the enzyme is discussed.
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PMID:The role of arginine residues in the function of D-glyceraldehyde-3-phosphate dehydrogenase. 21 10

When chicken breast muscle was homogenized in water, approximately 86% of the glyceraldehyde-3-phosphate dehydrogenase was associated with the particulate fraction. The enzyme was solubilized by increasing pH with a very marked increase in the pH range of 6.9 to 7.1. At low ionic strength (about 0.015), approximately 50% of the enzyme is solubilized at pH 7.5 and above. Increasing ionic strength also led to increased solubilization. In addition, there was a specific cation effect with Ca2+ greater than Mg2+ greater than K+ greater than Na+ at a constant ionic strength. Glyceraldehyde 3-phosphate and 2,3-bisphosphoglycerate were effective in partially solubilizing the enzyme. Solubilized glyceraldehyde-3-phosphate dehydrogenase can rebind to the particulate fraction of the homogenized muscle. The soluble form of the enzyme has a higher V and a higher Km (glyceraldehyde-3-phosphate) than the enzyme bound to the particulate fraction.
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PMID:Association of glyceraldehyde-3-phosphate dehydrogenase with the particulate fraction of chicken skeletal muscle. 24 Jun 91

The molecular basis of thermal stability of globular proteins is a highly significant yet unsolved problem. The most promising approach to its solution is the investigation of the structure-function relationship of homologous enzymes from mesophilic and thermophilic sources. In this context, D-glyceraldehyde-3-phosphate dehydrogenase has been the most extensively studied model system. In the present study, the most thermostable homolog isolated so far is described with special emphasis on the stability of the enzyme under varying solvent conditions. D-Glyceraldehyde-3-phosphate dehydrogenase from the hyperthermophilic eubacterium Thermotoga maritima is an intrinsically thermostable enzyme with a thermal transition temperature around 110 degrees C. The amino acid sequence, electrophoresis, and sedimentation analysis prove the enzyme to be a homotetramer with a gross structure similar to its mesophilic counterparts. The enzyme in the absence and in the presence of its coenzyme, NAD+, exhibits no drastic structural differences except for a 3% change in sedimentation velocity reflecting slight alterations in the quaternary structure of the enzyme. At low temperature, in the absence of denaturants, neither "cold denaturation" nor subunit dissociation are detectable. Guanidinium chloride and pH-dependent deactivation precede the decrease in fluorescence emission and ellipticity, suggesting a complex denaturation mechanism. An up to 3-fold activation of the enzyme at low guanidinium concentration may be interpreted in terms of a compensation of the tight packing of the thermophilic enzyme at low temperature. Under destabilizing conditions, e.g. moderate concentrations of chaotropic agents, low temperature favors denaturation. The effect becomes important in reconstitution experiments after preceding guanidinium denaturation; the reactivation yield at low temperature drops to zero, whereas between 35 and 80 degrees C reactivation exceeds 80%. Shifting the temperature from approximately 0 degrees C to greater than or equal to 30 degrees C releases a trapped tetrameric intermediate in a fast reaction. Concentration-dependent reactivation experiments prove renaturation of the enzyme to involve consecutive folding and association steps. Reconstitution at room temperature yields the native protein, in spite of the fact that the temperature of the processes in vitro and in vivo differ by more than 60 degrees C.
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PMID:Stability and reconstitution of D-glyceraldehyde-3-phosphate dehydrogenase from the hyperthermophilic eubacterium Thermotoga maritima. 136 31

The binding of a spin-labeled AMP analog to tetrameric glyceraldehyde-3-phosphate dehydrogenase from rabbit muscle is described. The spin label, perdeuterated and 15N-substituted 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, was attached to C-8 of AMP (C8-SL-AMP). Up to 8 equivalents of C8-SL-AMP bind per enzyme tetramer, i.e., 2 per monomer. Combining sites are the adenine subsite of the coenzyme-binding domain and the phosphate site. Glyceraldehyde 3-phosphate causes a conformational change in the enzyme that brings C8-SL-AMP molecules bound to adjacent R-axis-related subunits closer to one another by 0.2-0.3 nm and allows for spin-spin interaction between the nitroxide radicals. Similar, but less pronounced structural changes take place upon lowering the pH from 8 to 7. Addition of a single equivalent of NAD+ to a complex of the enzyme with 7.6 equivalents of C8-SL-AMP leads to the release of almost 4 C8-SL-AMP molecules. This supports our previous findings that binding of just one NAD+ molecule induces conformational changes in all four subunits.
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PMID:Interaction of glyceraldehyde-3-phosphate dehydrogenase with AMP as studied by means of a spin-labeled analog. 255 43

D-Glyceraldehyde-3-phosphate dehydrogenase (GAP-DH) is a protein containing no disulfide bonds; the guanidine HCl-denatured enzyme shows only a limited extent of refolding and reactivation upon dilution, and the enzyme is particularly prone to aggregation during the dilution process. With increasing GAPDH concentration, reactivation decreases and aggregation increases. The presence of protein disulfide isomerase in the dilution mixture markedly increases reactivation of GAPDH and at the same time prevents the aggregation of GAPDH as shown by light-scattering measurements. It is suggested that upon dilution, denatured GAPDH is faced with two competing processes of correct folding and assembly to yield the native enzyme and non-productive association of the partially refolded species to form aggregates. Independent of the isomerase activity as no disulfide bond is present in GAPDH, protein disulfide isomerase assists the refolding of GAPDH to its active state by suppressing aggregation in a way closely similar to the action of chaperones.
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PMID:Chaperone-like activity of protein disulfide isomerase in the refolding of a protein with no disulfide bonds. 792 25

The structural and functional properties of chloroplast glyceraldehyde-3-P-dehydrogenase I (D-Glyceraldehyde-3-phosphate: NADP oxidoreductase (phosphorylating) EC 1.2.1.13) from Spinacia oleracea were investigated by limited proteolysis. The enzyme is insensitive to trypsin and chymotrypsin, while Staphylococcus aureus V8 protease cleaves the C-terminal region of its subunits. Subunit A (36 kDa) is only partially cleaved at Glu 317. No intact subunit B (39 kDa) is found at the end of the proteolytic experiment: two forms are originated from this subunit which is cleaved at Glu 342 and Glu 320. Proteolytic cleavage at these sites does not significantly alter enzymatic activity, but leads to destabilization of the protein. Unlike the intact parent enzyme (600 kDa) the cleaved enzyme behaves as a 150-kDa species in size exclusion chromatography.
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PMID:Limited proteolysis of chloroplast glyceraldehyde-3-phosphate dehydrogenase (NADP) from Spinacia oleracea. 835 35

D-Glyceraldehyde irreversibly inhibited rat liver glucokinase in a concentration-dependent manner. The inactivation of glucokinase by glyceraldehyde was blocked by the presence of its substrates such as glucose and mannose. Glucokinase was highly sensitive to glyceraldehyde compared with some other glycolytic enzymes (from animal tissues) including hexokinase, glucose-6-phosphate isomerase, 6-phosphofructokinase, glyceraldehyde-3-phosphate dehydrogenase, and pyruvate kinase. The amino acid analysis of untreated and glyceraldehyde-treated glucokinase suggested that glyceraldehyde-induced inactivation of glucokinase is caused by glycation of Lys residues of the enzyme by the triose. Treatment of pancreatic islets with 6 mM glyceraldehyde for 1 h at 37 degrees C caused both inactivation of glucokinase and inhibition of glucose-induced insulin secretion. Another glucose-phosphorylating enzyme (hexokinase) in pancreatic islets, however, was little affected by glyceraldehyde. In addition, glyceraldehyde did not affect the insulin secretory responses of islets to nonglucose secretagogues such as glyceraldehyde and Leu. When pancreatic islets were cultured with a lower concentration (1 mM) of glyceraldehyde for a longer time (17 h) in the presence of 10 mM glucose to mimic the in vivo conditions, both glucokinase activity and glucose-induced insulin secretion were again decreased. This study demonstrates that glucose-induced insulin secretion is impaired by glyceraldehyde through the inactivation of glucokinase. The implication of this finding in the pathophysiology of type II diabetes is discussed.
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PMID:Inhibition of glucose-induced insulin secretion through inactivation of glucokinase by glyceraldehyde. 851 67

D-Glyceraldehyde (D-GLYC) is usually considered to be a stimulator of insulin secretion but theoretically can also form reactive oxygen species (ROS), which can inhibit beta cell function. We examined the time- and concentration-dependent effects of D-GLYC on insulin secretion, insulin content, and formation of ROS. We observed that a 2-h exposure to 0.05-2 mM D-GLYC potentiated glucose-stimulated insulin secretion (GSIS) in isolated Wistar rat islets but that higher concentrations inhibited GSIS. A 24-h exposure to 2 mm D-GLYC inhibited GSIS, decreased insulin content, and increased intracellular peroxide levels (2.14 +/- 0.31-fold increase, n = 4, p < 0.05). N-Acetylcysteine (10 mM) prevented the increase in intracellular peroxides and the adverse effects of d-GLYC on GSIS. In the presence of 11.1 but not 3.0 mm glucose, koningic acid (10 microM), a specific glyceraldehyde-3-phosphate dehydrogenase inhibitor, increased intracellular peroxide levels (1.88 +/- 0.30-fold increase, n = 9, p < 0.01) and inhibited GSIS (control GSIS = p < 0.001; koningic acid GSIS, not significant). To determine whether oxidative phosphorylation was the source of ROS formation, we cultured rat islets with mitochondrial inhibitors. Neither rotenone or myxothiazol prevented D-GLYC-induced increases in islet ROS. Adenoviral overexpression of manganese superoxide dismutase also failed to prevent the effect of D-GLYC to increase ROS levels. These observations indicate that exposure to excess D-GLYC increases reactive oxygen species in the islet via non-mitochondrial pathways and suggest the hypothesis that the oxidative stress associated with elevated D-GLYC levels could be a mechanism for glucose toxicity in beta cells exposed chronically to high glucose concentrations.
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PMID:D-Glyceraldehyde causes production of intracellular peroxide in pancreatic islets, oxidative stress, and defective beta cell function via non-mitochondrial pathways. 1521 33


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