Substrate Independence of Molecular Weight of Triphosphopyridine Nucleotide-specific Isocitrate Dehydrogenase

Feedback inhibition of an allosteric triphosphopyridine nucleotide-specific isocitrate dehydrogenase.

Evidence is presented for the concerted inhibition of a TPN+-specXc isocitrate dehydrogenase from Crifhidia fascicutafa by two biosynthetic intermediates, oxalacetate and glyoxylate. This inhibition is competitive with substrate, and the presence of either inhibitory compound greatly increases the afhnity of the enzyme for the second. This inhibition has been shown not to be due to the formatio...

A glutamyl residue in the active site of triphosphopyridine nucleotide-dependent isocitrate dehydrogenase of pig heart.

The maximum velocity of the reaction catalyzed by the pig heart TPN-specific isocitrate dehydrogenase depends on the basic form of an enzymatic group of pK 5.7. This pK is independent of temperature from 10-30” and increases in 20% ethanol, suggesting the ionization of a carboxyl group. The enzyme is inactivated by incubation at pH 7.0 with 1 cyclohexyl3 (2 morpholinoethyl) carbodiimide either ...

Isolation and some properties of the triphosphopyridine nucleotide isocitrate dehydrogenase from Bacillus stearothermophilus.

The TPN+-dependent isocitrate dehydrogenase from Bacillus stearothermophilus (NCA 2184) has been isolated and purified approximately lOOO-fold. The preparation described is homogenous as judged by sedimentation equilibrium and disc gel electrophoresis. The weight average molecular weight estimated by sedimentation equilibrium analysis is 92,500. In 6 M guanidine hydrochloride-l mM dithiothreito...

Kinetic evidence for the dimerization of the triphosphopyridine nucleotide-dependent isocitrate dehydrogenase from pig heart.

Re-evaluation of molecular weight of pig heart NAD-specific isocitrate dehydrogenase.

NAD-specific pig heart isocitrate dehydrogenase was earlier reported, on the basis of gel filtration experiments, to have a molecular weight of approximately 340,000. In the present study, the enzyme is shown by equilibrium ultracentrifugation to have a weight average molecular weight of approximately 224,000 which can be attributed to a rapidly associating-dissociating protein system. The resu...