<p>Bacterial isocitrate dehydrogenases (IDHs) (<db_xref db="EC" dbkey="1.1.1.42"/>) can be classified into two types on the basis of their subunit structure. One is a homodimer consisting of subunits of about 40-45 kDa, which exists in many bacterial species including Escherichia coli. The other is a monomer with a molecular mass of 80-100 kDa, which has been reported in several bacteria including Azotobacter vinelandii, Vibrio parahaemolyticus and Corynebacterium glutamicum. Although bacterial monomeric and dimeric IDHs catalyse the same reaction, homology of amino acid sequence is hardly found between both types of IDHs [<cite idref="PUB00055420"/>]. </p><p>Several NAD- or NADP-dependent dehydrogenases, including 3-isopropylmalate dehydrogenase, tartrate dehydrogenase, and the dimeric forms of isocitrate dehydrogenase, share a nucleotide binding domain unrelated to that of lactate dehydrogenase and its homologues. These enzymes dehydrogenate their substrates at a H-C-OH site adjacent to a H-C-COOH site; the latter carbon, now adjacent to a carbonyl group, readily decarboxylates. Bacterial dimeric NADP-dependent isocitrate dehydrogenases resemble their NAD-dependent counterparts and 3-isopropylmalate dehydrogenase (an NAD-dependent enzyme) more closely than they resemble eukaryotic NADP-dependent isocitrate dehydrogenases.</p> <p>This entry represents the bacterial NADP-dependent dimeric isocitrate dehydrogenases.</p>