title: Ethanolamine ammonia-lyase: inactivation of the holoenzyme by N2O and the mechanism of action of Coenzyme B12.
abstract: Functional ethanolamine ammonia-lyase is inactivated by N2O as well as by O2, indicating that the active form of coenzyme B12 is an enzyme-bound corrin derivative in which the Co-C bond of the coenzyme is broken and the cobalt ion is in the +1 state of oxidation. The nucleoside fragment formed in the process of coenzyme activation is tentatively identified as 4',5'-didehydro-5'-deoxyadenosine. A mechanism of action of ethanolamine ammonia-lyase is formulated in analogy to that of DL-1,2-Propanediol dehydrase and compared to proposed alternative reaction schemes.
mesh_terms: D000642:Ammonia-Lyases / Q000378:metabolism*; D001665:Binding Sites; D003013:Clostridium / Q000201:enzymology; D004983:Ethanolamines; D007700:Kinetics; D009609:Nitrous Oxide / Q000494:pharmacology*; D011485:Protein Binding; D013997:Time Factors; D014805:Vitamin B 12 / Q000494:pharmacology*
chemical_list: D004983:Ethanolamines; D000642:Ammonia-Lyases; D009609:Nitrous Oxide; D014805:Vitamin B 12