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  • Title: A structural basis for substrate selectivity and stereoselectivity in octopine dehydrogenase from Pecten maximus.
    Author: Smits SH, Mueller A, Schmitt L, Grieshaber MK.
    Journal: J Mol Biol; 2008 Aug 01; 381(1):200-11. PubMed ID: 18599075.
    Abstract:
    Octopine dehydrogenase [N(2)-(D-1-carboxyethyl)-L-arginine:NAD(+) oxidoreductase] (OcDH) from the adductor muscle of the great scallop Pecten maximus catalyzes the reductive condensation of l-arginine and pyruvate to octopine during escape swimming. This enzyme, which is a prototype of opine dehydrogenases (OpDHs), oxidizes glycolytically born NADH to NAD(+), thus sustaining anaerobic ATP provision during short periods of strenuous muscular activity. In contrast to some other OpDHs, OcDH uses only l-arginine as the amino acid substrate. Here, we report the crystal structures of OcDH in complex with NADH and the binary complexes NADH/l-arginine and NADH/pyruvate, providing detailed information about the principles of substrate recognition, ligand binding and the reaction mechanism. OcDH binds its substrates through a combination of electrostatic forces and size selection, which guarantees that OcDH catalysis proceeds with substrate selectivity and stereoselectivity, giving rise to a second chiral center and exploiting a "molecular ruler" mechanism.
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