Peptide fragmentation suitable for solid-phase microsequencing. Use of N-bromosuccinimide and BNPS-skatole (3-bromo-3-methyl-2-[(2-nitrophenyl)thio]-3H-indole).

BNPS-skatole (3-bromo-3-methyl-2-(2-nitrophenyl)thiol-3H-indole) and N-bromosuccinimide have been used to specifically cleave at peptide bonds after amino acids with available C-gamma=C-delta double bonds, i.e. tryptophan, tyrosine and histidine. The resulting C-terminal lactones conveniently attach to amino-glass supports for sequencing with DABITC (4-NN-dimethylaminoazobenzene 4'-isothiocyanate). Also, peptides having such C-termini, i.e. from a chymotryptic digest, can be readily made to react with these reagents and thus be easily attached and sequenced by solid-phase methods.