Insights into the mechanisms of adenosylcobalamin (coenzyme B12)-dependent enzymes from rapid chemical quench experiments

Glutamate mutase is one of a group of adenosylcobalamin-dependent enzymes that use free radicals to catalyse unusual and chemically difficult rearrangements involving 1,2-migrations of hydrogen atoms. A key mechanistic feature of these enzymes is the transfer of the migrating hydrogen atom between substrate, coenzyme and product. The present review summarizes recent experiments from my laboratory that have used rapid chemical quench techniques to identify intermediates in the reaction and probe the mechanism of hydrogen transfer through a variety of pre-steady-state kinetic isotope effect measurements.