Evidence for the presence of two nonidentical subunits in NAD-dependent isocitrate dehydrogenase of pig heart.

Binding of ligands to half of subunits of NAD-dependent isocitrate dehydrogenase from pig heart. Binding of manganous ion, isocitrate, ADP and NAD.

NAD-dependent isocitrate dehydrogenase from pig heart contains three types of subunits of slightly different molecular weights in an approximate ratio of 2:l:l. Ultrafiltration binding experiments at pH 6.1 indicate 1 binding site for every 2 subunits for several different ligands. The metal activator, Mn2+, binds to isocitrate dehydrogenase in the absence of other ligands ( K D = 115 p ~ ) . M...

Isocitrate binding at two functionally distinct sites in yeast NAD+-specific isocitrate dehydrogenase.

Yeast NAD(+)-specific isocitrate dehydrogenase (IDH) is an octamer containing two types of homologous subunits. Ligand-binding analyses were conducted to examine effects of residue changes in putative catalytic and regulatory isocitrate-binding sites respectively contained in IDH2 and IDH1 subunits. Replacement of homologous serine residues in either subunit site, S98A in IDH2 or S92A in IDH1, ...

Isocitrate dehydrogenase from bovine heart: primary structure of subunit 3/4.

Bovine NAD(+)-dependent isocitrate dehydrogenase was shown previously to contain four subunits of approx. 40 kDa (subunits 1-4) possessing different peptide maps and electrophoretic properties [Rushbrook and Harvey (1978) Biochemistry 17, 5339-5346]. In this study the heterogeneity is confirmed using enzyme purified by updated methods and from single animals, ruling out allelic variability. Sub...

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...