In enzymology, a 3-hydroxyisobutyrate dehydrogenase (EC1.1.1.31) also known as β-hydroxyisobutyrate dehydrogenase or 3-hydroxyisobutyrate dehydrogenase, mitochondrial (HIBADH) is an enzyme[5] that in humans is encoded by the HIBADHgene.[6]
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 3-hydroxy-2-methylpropanoate:NAD+ oxidoreductase. This enzyme participates in valine, leucine and isoleucine degradation.
Function
3-hydroxyisobutyrate dehydrogenase is a tetrameric mitochondrial enzyme that catalyzes the NAD+-dependent, reversible oxidation of 3-hydroxyisobutyrate, an intermediate of valine catabolism, to methylmalonate semialdehyde.[6]
Structural studies
As of late 2007, five structures have been solved for this class of enzymes, with PDB accession codes 1WP4, 2CVZ, 2GF2, 2H78, and 2I9P.