Evidence for a Mechanism Involving Transient Fragmentation in Carbon Skeleton Rearrangements Dependent on Coenzyme B₁₂

Abstract

Enzyme kinetics and EPR spectroscopy provide evidence that in the reversible rearrangement of (S)-glutamate (1) to (2S, 3S)-3-methylaspartate (2), which is catalyzed by the coenzyme B12 dependent glutamate mutase from Clostridium cochlearium, the substrate 1 fragments into acrylate (3) and glycine radical (4), which recombine to 2. Ado-CH2-Cbl  5′-adenosylcobalamin (coenzyme B12).