Patent ID: 7670841

Claim:
A method for analyzing the C-terminal amino acid sequence of a peptide being maintained in a state that it is bound on a gel carrier, which method comprises steps of: releasing the C-terminal amino acids successively from the peptide being bound on the gel carrier by chemical procedure to prepare a mixture containing said original peptide and a series of peptidyl reaction products produced therefrom, analyzing the original peptide and said series of the peptidyl reaction products produced at the releasing step by means of mass spectrometry to measure the decreases in molecular weight associated with the successive release of the C-terminal amino acid, and identifying a series of the C-terminal amino acids removed successively, based on a series of the measured decreases in molecular weight, wherein the gel carrier is a polyacrylamide gel, and the releasing step comprises: a sub-step (1) of conducting dehydration treatment for removing out the water solvent impregnated into the gel carrier, a sub-step (2) of immersing the gel carrier, on which the peptide is still bound after said step of dehydration treatment, in a mixed solution of an alkanoic acid anhydride and a perfluoroalkanoic acid dissolved in a dipolar aprotic solvent to allow the alkanoic acid anhydride and the perfluoroalkanoic acid to act on the peptide being kept in the bound state; and a sub-step (3) of removing the mixed solution from the gel carrier by dilution with use of a polar aprotic solvent; wherein in the sub-step (2), the successive release of the C-terminal amino acids results from the reaction process with use of the mixed solution in which formed is a 5-oxazolone-ring structure represented by the following general formula (111): where R1 is a side chain of the C-terminal amino acid of the peptide and R2 is a side chain of the amino acid residue positioned just before the C-terminal amino acid, followed by the cleavage of the 5-oxazolone-ring.