Mutagenesis of morphinone reductase induces multiple reactive configurations and identifies potential ambiguity in kinetic analysis of enzyme tunneling mechanisms

Stopped-flow spectroscopy has demonstrated that reduction of the FMN cofactor by NADH in N189A morphinone reductase (MR) in multiphasic, thus identifying four different reactive configurations of the MR-NADH complex. The analysis has helped in deriving the mechanistic information regarding multiple reactive configurations of the same enzyme-coenzyme complex by using stopped-flow methods.