Amino acid sequences of two cyanogen bromide fragments cb ii and cb iii, and the complete sequence of ala chain of ricin d

Tryptic peptides from two cyanogen bromide (CNBr) fragments CB II and CB III of the Ala chain of ricin D were sequenced by manual Edman degradation. Chymotryptic or peptic peptides from the two fragments were isolated by Dowex 1 x 2 column chromatography to obtain overlaps for the tryptic peptides, and the complete amino acid sequences of fragments CB II and CB III were established. The amino acid residues in fragments CB II and CB III accounted for 75 and 45 residues, respectively, of 260 residues in the Ala chain. These sequences together with the sequence of fragment CB I described in the preceding paper established the complete sequence of the 260 amino acid residues in the Ala chain. Some structural characteristics of the protein are also discussed.