3-hydroxyisobutyrate dehydrogenase

In is_associated_with::enzymology, a 3-hydroxyisobutyrate dehydrogenase also known as β-hydroxyisobutyrate dehydrogenase or 3-hydroxyisobutyrate dehydrogenase, mitochondrial (HIBADH) is an is_associated_with::enzyme that in humans is encoded by the HIBADH is_associated_with::gene.

3-Hydroxyisobutyrate dehydrogenase catalyzes the is_associated_with::chemical reaction:


 * 3-hydroxy-2-methylpropanoate + NAD+ $$\rightleftharpoons$$ 2-methyl-3-oxopropanoate + NADH + H+

Thus, the two substrates of this enzyme are is_associated_with::3-hydroxy-2-methylpropanoate and NAD+, whereas its 3 products are is_associated_with::2-methyl-3-oxopropanoate, NADH, and H+.

This enzyme belongs to the family of is_associated_with::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 is_associated_with::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, 5 structures have been solved for this class of enzymes, with PDB accession codes, , , , and.