Biochemical catalysis involving coenzyme B-12: a rational stepwise mechanistic interpretation of vicinal interchange rearrangements.
A mechanism is proposed for the catalytic action of coenzyme B-12 which is consistent with current knowledge of organometallic reactions and with the experimental data now available from biochemical studies. A key feature of the proposal is an electrocyclic cleavage of the coenzyme that reduces cobalt and also leads to a 1,19-seco-corrin. The seco-corrin serves as a tridentate ligand about Co(I). This arrangement permits the metal to take part in the kinds of organometallic reactions that are ideal for coenzyme B-12 catalysis, including oxidative addition and its reverse, reductive elimination. It is further proposed that the rearrangement steps involve cobaltcarbene complexes.
D002384:Catalysis; D003035:Cobalt; D003038:Cobamides / Q000378:metabolism*; D003839:Deoxyadenosines; D008024:Ligands; D008958:Models, Molecular; D008968:Molecular Conformation; D010084:Oxidation-Reduction
D003038:Cobamides; D003839:Deoxyadenosines; D008024:Ligands; D003035:Cobalt