Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.2.1.13 (glyceraldehyde-3-phosphate dehydrogenase)
 6,511 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ammonium sulfate, a typical component of crystallization media of proteins, stabilizes an inactive conformation of pig muscle glyceraldehyde-3-phosphate dehydrogenase. In fact, in the presence of ammonium sulfate the reconstitution of the catalytically active holoenzyme from the apoenzyme and NAD is not instantaneous, as in the case of enzymes from Bacillus stearothermophilus and the Mediterranean lobster Palinurus vulgaris. With pig muscle enzyme, at pH 6.0, the time course of formation of the characteristic Racker band can be monitored by a rapid mixing stopped flow technique. Activation follows a single exponential curve with a rate constant independent of the concentration of both NAD and protein and, therefore, appears to be limited by a slow protein isomerization (k = 7 +/- 2 s-1). Accordingly, when the apoenzyme is simultaneously exposed to NAD and either glyceraldehyde 3-phosphate or 1,3-bisphosphoglycerate, the ensuing reactions (the redox and the acylation steps, respectively) are kinetically limited by the same protein isomerization. At pH 7.0 and 8.0, however, two among the four active sites react with NAD at an unmeasurably high rate, while the other two sites behave as they do at pH 6.0. When the pig muscle apoenzyme is preincubated and allowed to react with either glyceraldehyde 3-phosphate or 1,3-bisphosphoglycerate before the rapid mixing with NAD, both the redox reaction and the NAD-dependent activation of apo-acyl-enzyme toward arsenolysis become unmeasurably fast. Similarly, when the sulfate in the medium is replaced by ions such as phosphate and citrate, the reconstitution of the active holoenzyme is practically instantaneous. Thus, the slow protein isomerization observed in the presence of sulfate and abolished by competing substrates and anions is diagnostic of a structural state of the pig muscle apoenzyme, which is induced by sulfate ions bound within the enzyme active site.
 ...
PMID:Kinetic evidence for a reversible isomerization of pig muscle glyceraldehyde-3-phosphate dehydrogenase in its crystallization medium. 336 57

The catalytic activity and activity changes during denaturation by guanidine hydrochloride of glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase and alpha-chymotrypsin in crystalline state and in solution have been compared. The catalytic activities are lower in crystalline state than in solution. Enzymes in crystalline state are more stable than in solution during denaturation by guanidine hydrochloride. Ammonium sulfate has different effects on catalytic activities of different enzymes and shows protection on all enzymes studied during denaturation by guanidine hydrochloride. The protection is more obvious at high concentrations of guanidine hydrochloride than at low concentrations. It is suggested that the flexibility or mobility of enzyme is required for the catalytic activity and related to the stability of enzymes. Enzymes with less flexibility or mobility are more stable.
 ...
PMID:Comparison between catalytic activity and activity changes during denaturation by guanidine hydrochloride of enzymes in crystalline state and in solution. 831 51

Ammonium sulfate chromatography has been employed to separate glyceraldehyde 3-phosphate dehydrogenases (GPD) of Sinapis alba cotyledons of various developmental stages. Cotyledons of dark-grown seedlings possess one major NAD-specific enzyme designated NAD-GPD I. Irradiation with continuous far red light leads to a strong increase in NADP-GPD activity and to the formation of a second NAD activity designated NAD-GPD II. These two activities occur in a constant ratio during cotyledon development, and they are eluted together in ammonium sulfate chromatography. In a later stage of cotyledon development the light-dependent increase in NAD-GPD II is matched by an equivalent decrease in NAD-GPD I. These data suggest that the chloroplast marker enzyme NADP-GPD (EC 1.2.1.13) also has NAD activity and that the light-dependent formation of this bifunctional enzyme is correlated with activity changes of the NAD-GPD of cytoplasmic glycolysis (EC 1.2.1.12).
 ...
PMID:Glyceraldehyde 3-Phosphate Dehydrogenases and Glyoxylate Reductase: II. Far Red Light-Dependent Development of Glyceraldehyde 3-Phosphate Dehydrogenase Isozyme Activities in Sinapis Alba Cotyledons. 1665 22