NADP-dependent isocitrate dehydrogenase from the mussel Mytilus edulis L. 2. Kinetic studies.
The kinetic mechanism for NADP-dependent isocitrate dehydrogenase from the digestive gland of the mussel Mytilus edulis has been investigated. Initial-rate studies and substrate-analogue and product-inhibition patterns are consistent with a rapid-equilibrium random-ordered reaction mechanism, both with respect to substrate addition and product release. Product inhibition by NADPH is non-competitive versus D-isocitrate concentrations. 2-Oxoglutarate inhibition is competitive versus D-isocitrate at all NADP concentrations. The inhibition by 2-oxoglutarate versus NADP is either non-competitive or uncompetitive. Tricarballylic acid (a substrate analogue of D-isocitric acid) gives competitive inhibition versus D-isocitrate at all NADP levels and mixed inhibition versus NADP, at sub-saturating levels of D-isocitrate.
D000818:Animals; D049872:Bivalvia / Q000201:enzymology*; D004064:Digestive System / Q000201:enzymology; D007521:Isocitrate Dehydrogenase / Q000378:metabolism*; D007656:Ketoglutaric Acids / Q000494:pharmacology; D007700:Kinetics; D008433:Mathematics; D009249:NADP / Q000494:pharmacology; D010084:Oxidation-Reduction; D014233:Tricarboxylic Acids / Q000494:pharmacology
D007656:Ketoglutaric Acids; D014233:Tricarboxylic Acids; D009249:NADP; D007521:Isocitrate Dehydrogenase; C028021:tricarballylic acid