Old yellow enzyme: stepwise reduction of nitro-olefins and catalysis of aci-nitro tautomerization.
The Old Yellow Enzyme has been shown to catalyze efficiently the NADPH-linked reduction of nitro-olefins. The reduction of the nitro-olefin proceeds in a stepwise fashion, with formation of a nitronate intermediate that is freely dissociable from the enzyme. The first step involves hydride transfer from the enzyme-reduced flavin to carbon 2 of the nitro-olefin. The protonation of the nitronate at carbon 1 to form the final nitroalkane product also is catalyzed by the enzyme and involves Tyr-196 as an active site acid/base. This residue also is involved in aci-nitro tautomerization of nitroalkanes, the first example of a nonredox reaction catalyzed by the enzyme.
Meah
Y
Y
Department of Biological Chemistry, The University of Michigan Medical School, Ann Arbor, MI 48109, USA.
Massey
V
V
D000475:Alkenes / Q000378:metabolism*; D002384:Catalysis; D007700:Kinetics; D009252:NADPH Dehydrogenase / Q000378:metabolism*; D010084:Oxidation-Reduction; D010940:Plant Proteins / Q000378:metabolism*; D013379:Substrate Specificity
D000475:Alkenes; D010940:Plant Proteins; D009252:NADPH Dehydrogenase