3-hydroxyisobutyrate dehydrogenase


In enzymology, a 3-hydroxyisobutyrate dehydrogenase also known as β-hydroxyisobutyrate dehydrogenase or 3-hydroxyisobutyrate dehydrogenase, mitochondrial is an enzyme that in humans is encoded by the HIBADH gene.
3-Hydroxyisobutyrate dehydrogenase catalyzes the chemical reaction:
The two substrates of this enzyme are 3-hydroxyisobutyric acid and oxidised nicotinamide adenine dinucleotide. Its products are methylmalonic acid semialdehyde, reduced NADH, and a proton.
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.

Structural studies

As of late 2007, five structures have been solved for this class of enzymes, with PDB accession codes,,,, and.