| 摘要 |
Provided is a novel process for chemically converting a peptide chain into a peptide thioester. The inventors paid attention to the cysteine residue of a peptide chain. As a result, the following has been found. When a -C(=X)-R 1 group is introduced to the thiol group of the cysteine residue and then the resulting peptide is reacted with a compound having a leaving group represented by the formula: -NH-C(=Y)NHR 3 in an organic solvent, the -NH-C(=Y)NHR 3 group binds via addition reaction to the carboxyl group of the N-terminal-side peptide bond of the cysteine residue, whereby the peptide bond is cleaved and the C-terminal-side peptide fragment is cut off. Further, when the resulting peptide chain having the -NH-C(=Y)NHR 3 group is reacted with a thiol in a buffer solution, a thiol exchange reaction occurs, namely, the thiol group of the thiol binds to the carbonyl carbon to which the -NH-C(=Y)NHR 3 group has bound, whereby the -NH-C(=Y)NHR 3 group is eliminated. Thus, the conversion into a peptide thioester is attained. |
