C-terminal analysis of proteins and peptides

A chemical method for C-terminal sequencing has been used to analyze the C-terminus of proteins and peptides, which can be converted to proteinyl alkylated thiohydantoin (proteinyl-ATH) or peptidyl-ATH via activated with acetic anhydride, coupled with [NCS](-) and alkylated with bromomethylene. The C-terminal ATH-amino acid can be cleaved and detected at 254 nm. The C-terminal sequences with varied lengths have been obtained from natural and recombinant proteins and peptides by the C-terminal analysis, and modifications and mutations of C-terminus have been found. By this method, important information on C-terminus of proteins and peptides can be obtained for the identification of recombinant products and sythetic peptides. At presant, starting with samples of 1-2 nmole, C-terminal of 3-5 residues or that of over 10 residues in some case, can be successfully determined.