    1.1.1.283 | (S)-lactaldehyde + NADP+ = 2-oxopropanal + NADPH + H+ |
catalytic mechanism involving Ser127, Tyr165, and Lys169, overview. In the first step, the hydroxyl groups of the Ser127 and Tyr165 residues form hydrogen bonds with the carbonyl oxygen of isovaleraldehyde, stabilizing its position. Subsequently, the hydroxyl group of Tyr165 donates a hydrogen to the carbonyl through deprotonation. Concomitantly, NADPH releases a hydrogen from the B-face of the nicotinamide ring onto the susceptible position of the carbonyl group. Thus, the carbonyl group is reduced to an alcohol group, and the isoamyl alcohol and NADP+ are produced. Upon reduction of the carbonyl group, the hydrogen bond between the side chain of Tyr165 and isoamyl alcohol is broken. With the redox state change, the conformation of NADP+ also may change, accompanied by the opening of the interdomain cleft for the release of the product |
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