Suicide inactivation in adenosylcobalamin-dependent enzymes

Adenosylcobalamin (AdoCbl) dependent enzymes exploit organic radicals for rearrangement of adjacent groups. Their dependence on radicals for catalysis results in the possibility of irreversible inactivation. An allylic analogue of AdoCbl has been synthesized and its corresponding activity assessed with AdoCbl-dependent diol dehydratase (DDH). Suicide inactivation of Ethanolamine ammonia lyase (EAL), an AdoCbl-dependent enzyme that catalyses the irreversible deamination of vicinal amino alcohols to produce their corresponding aldehydes, by substrate analoguehydroxyethylhydrazine (HEH) has been postulated to result from the failure of Adȯ to be regenerated due to inability of the hydrazinium radical cation to capture a hydrogen atom from Ado-H.