Function
3-Isopropylmalate dehydrogenase (IMDH) catalyzes the oxidative decarboxylation of 3-isopropylmalate (3IPM) to 2-oxo-4-methylvalerate. This reaction is a step in the biosynthesis of leucine in bacteria and fungi. IMDH uses NAD as a cofactor. IMDH is a bifunctional enzyme that catalyzes dehydrogenation and decarboxylation in the presence of NAD and a divalent cation[1].
Structural highlights
3-isopropylmalate dehydrogenase complex with 3-isopropylmalate, glycerol, NAD, PMSF, Mn+2 and K- ions.
IMDH active site containing the NAD cofactor is located between 2 subunits and contains the substrate and Mn+2 and K- ions[2]. Water molecules shown as red spheres.
MN coordination site.
K coordination site.
3-isopropylmalate binding site.
Whole IMDH active site.
- ↑ Martignon S, Rossi F, Rizzi M. Expression, purification and characterisation of Haemophilus influenzae 3-isopropylmalate dehydrogenase (LeuB). Protein Pept Lett. 2007;14(8):822-7. PMID:17979826
- ↑ Pallo A, Olah J, Graczer E, Merli A, Zavodszky P, Weiss MS, Vas M. Structural and energetic basis of isopropylmalate dehydrogenase enzyme catalysis. FEBS J. 2014 Sep 11. doi: 10.1111/febs.13044. PMID:25211160 doi:https://dx.doi.org/10.1111/febs.13044
