Reaction: (1) isocitrate + NAD+ = 2-oxoglutarate + CO2 + NADH
(2) (1R,2S)-1-hydroxybutane-1,2,4-tricarboxylate + NAD+ = 2-oxoadipate + CO2 + NADH + H+
Other name(s): homoisocitrateisocitrate dehydrogenase; PH1722
Systematic name: isocitrate(homoisocitrate):NAD+ oxidoreductase (decarboxylating)
Comments: Requires Mn2+ and K+ or NH4+ for activity. Unlike EC 188.8.131.52, isocitrate dehydrogenase (NAD+) and EC 184.108.40.206, homoisocitrate dehydrogenase, this enzyme, from Pyrococcus horikoshii, can use both isocitrate and homoisocitrate as substrates. The enzyme may play a role in both the lysine and glutamate biosynthesis pathways.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:
1. Miyazaki, K. Bifunctional isocitrate-homoisocitrate dehydrogenase: a missing link in the evolution of β-decarboxylating dehydrogenase. Biochem. Biophys. Res. Commun. 331 (2005) 341-346. [PMID: 15845397]