Mitochondrial 3-hydroxyisobutyrate dehydrogenase (HIBADH) catalyzes the reversible reaction of methylmalonyl semialdehyde and NADH + H+ to form beta-hydroxyisobutyrate and NAD+. The biochemical properties of human HIBADH are inferred from those of its better-studied porcine homologue (Robinson and Coon 1957). Unpublished crystallographic studies (PDB 2GF2) have shown the active enzyme to be a tetramer of HIBADH polypeptides whose aminoterminal 40 residues, a mitochondrial targeting sequence, have been removed.
Coon, MJ, Robinson, WG
3-hydroxyisobutyrate dehydrogenase activity of HIBADH tetramer [mitochondrial matrix]
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