Partial sequence of the N-terminal portion of the protein of cowpea chlorotic mottle virus

Abstract

The action of trypsin on cowpea chlorotic mottle virus (CCMV) at pH 7.4 caused the release of 25 amino acid residues from the N-terminal of the protein. Separation of peptides released during this digestion on cation exchange resins and determination of their N-termini gave 6 major peptides: the N-terminal peptide CH₃---C(=0)--- NH---(Lys, Thr₂, Ser, Gly₂, Val₂); Ala---Ala---Ala---Arg; Asn---Thr---Arg; Ala---Gln---Arg; Leu---Thr---Arg; and Lys---Asn---Lys---Arg. Some of these peptides were cleaved by nontryptic enzymes in the digestion. Peptides cleaved by trypsin from chymotrypsintreated virus were Lys, Arg, and Asn---Thr---Arg. This information and the isolation of peptides containing more than one arginine were assessed to propose the partial sequence of 25 residues in the N-terminal of CCMV protein.