The Arrangement of the Tryptic Peptides in the Coat Protein of the f2 Bacteriophage

Abstract

Abstract In separate experiments, involving chymotryptic and peptic digestion of the f2 coat protein, a sufficient number of overlap peptides were isolated to permit us to propose an unambiguous arrangement of the tryptic peptides in the intact coat protein. The assignment of linkages between tryptic peptides was made by comparing the amino acid compositions of chymotryptic and peptic peptides containing lysine and arginine with the compositions of the tryptic peptides. In some cases these assignments were confirmed by digesting the overlap peptides with trypsin and by end group determinations. The order proposed for the tryptic peptides is T11-T8-T4-T3-T7-T9-T5-T2-T10-T6-T1. Two chymotryptic peptides were isolated which were derived from the NH2-terminal region of the protein. The order and amino acid sequence of these peptides were determined, making it possible to establish the sequence of the first 7 residues from the NH2-terminal end of the protein. This sequence is: Ala-Ser-Asn-Phe-Thr-Gln-Phe.