Insights into the mechanism of flavoprotein-catalyzed amine oxidation from nitrogen isotope effects on the reaction of N-methyltryptophan oxidase. Academic Article uri icon

abstract

  • The mechanism of N-methyltryptophan oxidase, a flavin-dependent amine oxidase from Escherichia coli, was studied using a combination of kinetic isotope effects and theoretical calculations. The 15(kcat/Km) kinetic isotope effect for sarcosine oxidation is pH-dependent with a limiting value of 0.994-0.995 at high pH. Density functional theory calculations on model systems were used to interpret these isotope effects. The isotope effects are inconsistent with proposed mechanisms involving covalent amine-flavin adducts but cannot by themselves conclusively distinguish between some discrete electron-transfer mechanisms and a direct hydride-transfer mechanism, although the latter mechanism is more consistent with the energetics of the reaction.

author list (cited authors)

  • Ralph, E. C., Hirschi, J. S., Anderson, M. A., Cleland, W. W., Singleton, D. A., & Fitzpatrick, P. F

complete list of authors

  • Ralph, Erik C||Hirschi, Jennifer S||Anderson, Mark A||Cleland, W Wallace||Singleton, Daniel A||Fitzpatrick, Paul F

publication date

  • January 1, 2007 11:11 AM