Amino Acid Sequence of a Trypsin-Chymotrypsin Inhibitor, B-III, of Peanut (Arachis hypogaea)

Abstract

The amino acid sequence of peanut trypsin-chymotrypsin inhibitor, B-111, was determined by conventional methods. The limited proteolysis of B-Ill with trypsin indicated the reactive sites of B-III for trypsin to be Arg(10)-Arg(11) and Arg(38)-Ser(39). Comparison of the established sequence of B-III with those of other Bowman-Birk type double-headed protease inhibitors indicated that B-Ill has four amino acid insertions and one amino acid deletion. It is especially interesting that the amino acid residue in the P₁' position (No. 11) of the first reactive site for trypsin is arginine instead of serine, which seems to be conserved at the P, ' position of the reactive sites of all Bowman-Birk type protease inhibitors.