Covalent modification of lysine during the suicide inactivation of rat liver cytochrome P-450 by chloramphenicol

摘要: Abstract During the metabolism of [14C]chloramphenicol by a reconstituted monooxygenase system or intact liver microsomes from phenobarbital-treated rats, 14C-containing metabolite covalently bonded to cytochrome P-450, and enzyme was irreversibly inhibited. In both systems, approximately 95 per cent 14C that bound protein associated with P-450. presence 0.5% sodium dodecylsulfate, half proteins dissociated treatment 1 N hydroxylamine (pH 7.5) mild alkaline hydrolysis 10.5). Most hydroxylamine-labile protein-bound material readily degraded oxalate under conditions used digest P-450 proteolytic enzymes. The radiolabeled stable isolated as an amino acid adduct pronase digests 14C-labeled microsomal proteins. This identified N-ɛ-chloramphenicol oxamyl lysine based on co-chromatography synthetic compound release free plus chloramphenicol oxamic upon product protein. Evidence is presented modification at least partially responsible for suicide inactivation chloramphenicol.