Homoisocitrate dehydrogenase  In enzymology, a homoisocitrate dehydrogenase () is an enzyme that catalyzes the chemical reaction  Thus, the two substrates of this enzyme are (1R,2S)-1-hydroxybutane-1,2,4-tricarboxylate and NAD+, whereas its 4 products are 2-oxoadipate, CO2, NADH, and H+. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is (1R,2S)-1-hydroxybutane-1,2,4-tricarboxylate:NAD+ oxidoreductase (decarboxylating). Other names in common use include 2-hydroxy-3-carboxyadipate dehydrogenase, 3-carboxy-2-hydroxyadipate dehydrogenase, homoisocitric dehydrogenase, (−)-1-hydroxy-1,2,4-butanetricarboxylate:NAD+ oxidoreductase, (decarboxylating), 3-carboxy-2-hydroxyadipate:NAD+ oxidoreductase (decarboxylating), and HICDH. This enzyme participates in lysine biosynthesis. As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code .