RECOGNITION OF THE CARBOXY TERMINAL PEPTIDE IN CYANOGEN BROMIDE DIGESTS OF PROTEINS

摘要

A method is reported that allows carboxy-terminal peptides to be recognized in cyanogen bromide cleavage reactions. Recognition is based on mass spectrometric analysis of the peptide products before and after reaction with acidic methanol. Peptides generated from internal positions in the protein are terminated by homoserine lactone, which undergoes methanolysis to add 32 mass units. The peptide containing the original carboxyl terminus is converted to a methyl ester, with a mass increment of 14 Da.