Open AccessConcerning 1e- transfer in reduction by dihydronicotinamide: reaction of oxidized flavin and flavin radical with N-benzyl-1,5-dihydronicotinamide.
Author(s) -
Michael F. Powell,
Wah Hun Wong,
Thomas C. Bruice
Publication year - 1982
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.79.15.4604
Subject(s) - flavin group , chemistry , photochemistry , perchlorate , acetonitrile , hydride , redox , radical ion , medicinal chemistry , inorganic chemistry , organic chemistry , enzyme , hydrogen , ion
The rates of reaction of 5-ethyl-3-methyllumiflavinium perchlorate and 5-ethyl-3-methyllumiflavinyl radical with a NADH analogue, N-benzyl-1,4-dihydronicotinamide, were measured anaerobically in tert-butanol and 5% acetonitrile/95% tert-butanol solutions at 30 degrees C. The biphasic kinetics observed for the reaction of flavin radical with dihydronicotinamide were interpreted in terms of both a 1e- and a 2e- mechanism; the former was found to be inadequate based on experimental requirements of the mechanism. The dihydronicotinamide reacts preferentially with oxidized flavin rather than flavin radical, even when the concentration of oxidized flavin is at a concentration 5 orders of magnitude less than that of radical. These studies show that the "hydride" reduction of oxidized flavin by BNAH is more facile than is the 1e- reduction of flavin radical by BNAH.