Reaction: methylmalonyl semialdehyde + NADH + H+ <=> beta-hydroxyisobutyrate + NAD+
- in pathway: Branched-chain amino acid catabolism
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 Unpublished crystallographic studies (PDB 2GF2) have shown the active enzyme to be a tetramer of HIBADH polypeptides whose aminoterminal 40 residues, a mitochondrial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.
Reaction - small molecule participants:
NAD+ [mitochondrial matrix]
bHIBA [mitochondrial matrix]
H+ [mitochondrial matrix]
2M3OPROA [mitochondrial matrix]
NADH [mitochondrial matrix]
Reactome.org reaction link: R-HSA-508473
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Reaction input - small molecules:
hydron
2-methyl-3-oxopropanoate
NADH(2-)
Reaction output - small molecules:
NAD(1-)
3-hydroxyisobutyrate
Reactome.org link: R-HSA-508473