A FLUORESCENT METHOD FOR SELECTIVE ISOLATION OF TRYPTOPHAN-CONTAINING PEPTIDE : MODIFICATION OF TRYPTOPHAN RESIDUE IN A PROTEIN WITH A CHELATING AGENT, 2-CARBOXY-1-HYDROXY-4-NAPHTHYLMETHYLDIMETHYLSULFONIUM CHLORIDE

Protein was treated with 2-carboxy-1-hydroxy-4-naphthylmethyldime-thylsulfonium chloride to modify the tryptcphan residues in the chain. The product thus obtained was treated with trypsin and the tryptophan modified fragment (s) was selectively isolated by adsorption onto a Chelating Sepharose 6B column (Al^<3+> form). This procedure may also be extended to molecular biology.