title: Formation of delta1-acetoxytryptophan-62 in the oxidation of tryptophan-62 of hen egg-white lysozyme by N-bromosuccinimide in acetate buffer.
abstract: The reaction of equimolar amounts of N-bromosuccinimide and hen egg-white lysozyme in acetate buffer, under the conditions of Hayashi et al. (Hayashi, K., Imoto, T., Funatsu, G., and Funatsu, M. (1965), J. Biochem. (Tokyo) 58, 227), yields a protein mixture that has a time-dependent 13C-NMR spectrum. The initial natural-abundance 13C-NMR spectrum indicates the presence of about equal amounts of [oxindolealanine-62]lysozyme and [delta1-acetoxytryptophan-62]lysozyme. The latter converts to [oxindolealanine-62]lysozyme with a half-life of about 2 days at 25 degrees C and pH 3.9. Two observations indicate that the source of the acetyl group of delta1-acetoxytryptophan-62 is the acetate buffer. First, the spectrum of a lysozyme sample treated with N-bromosuccinimide in the presence of [1-13C]acetate yields a very strong acetyl ester carbonyl resonance. The time dependence of the intensity of this resonance yields a half-life of 44 h for [delta1-acetoxytryptophan-62]lysozyme. Second, the initial natural-abundance 13C-NMR spectrum of a lysozyme sample treated with N-bromosuccinimide in the absence of acetate indicates essentially complete conversion of tryptophan-62 into oxindolealanine.
mesh_terms: D000085:Acetates; D000818:Animals; D001665:Binding Sites; D001974:Bromosuccinimide; D002645:Chickens; D004529:Egg White; D006146:Guanidines; D009682:Magnetic Resonance Spectroscopy; D009113:Muramidase; D010084:Oxidation-Reduction; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D014364:Tryptophan / Q000032:analysis
chemical_list: D000085:Acetates; D006146:Guanidines; D014364:Tryptophan; D009113:Muramidase; D001974:Bromosuccinimide