Chemistry of trichosanthin: VII. The chemical cleavage of the tryptophanyl peptide bond in trichosanthin

The single tryptophan residue of trichosanthin was cleaved by the use of BNPS‐skatole reaction with STIG2 peptide fregment which was obtained from the tryptic digestion of N‐succinyl trichosanthin. After separation, the N‐terminal sequence of tryptophanyl C‐side peptide was determined by use of manual DABITC‐PITC double coupling sequencing method as follows: ‐Leu‐Ala‐Leu‐Ser‐Lys‐Gln‐Ile‐Gln‐Ile‐Ala‐.