Intrinsic Deuterium Kinetic Isotope Effects in Glutamate Mutase Measured by an Intramolecular Competition Experiment

Abstract

Intramolecular competition between hydrogen and deuterium atoms at the methyl group of methylaspartate was used to measure the intrinsic primary deuterium isotope effect for 5′-deoxyadenosine formation in a B12 enzyme. The value is much smaller than expected based on measurements on other B12 enzymes and model systems. This strongly suggests that glutamate mutase modulates the transition state for hydrogen transfer.