Crystallization of Bowman-Birk type protease inhibitor (peanut) and its complex with trypsin.

Crystallization and preliminary crystallographic study of Bowman-Birk type protease inhibitors, A-I, A-II, and B-III from peanut seeds (Arachis hypogaea), and of the A-II + trypsin complex were carried out. A-II, with 70 amino acid residues, crystallizes in a trigonal system, P3(1)21 (or P3(2)21), a = 71.8, c = 65.9 A, Z = 12 or 18. The A-I crystal is isomorphous with that of A-II, indicating that the N-terminal residues are in a disordered state in both crystals. The B-III crystal is monoclinic, C2, a = 119.6, b = 69.6, c = 94.2 A, beta = 115.1 degrees, Z is about 40. The A-II + trypsin complex crystallizes in an orthorhombic system, P2(1)2(1)2(1), a = 55.5, b = 56.0, c = 182.1 A, Z = 4.