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-11 + trypsin complex were carried out. A-11, with 70 amino acid residues, crystallizes in a trigonal system, P3121 (or P3221), a=71.8, c=65.9 Â, 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= 94.2Â, β= 115.1°, Z is about 40. The A-II + trypsin complex crystallizes in an orthorhombic system, P212121, a=55.5, b= 56.0, c=182.1 Â, Z=4.