CRYSTALLIZATION AND PRELIMINARY CRYSTALLOGRAPHIC DATA OF THE ALPHA-AMYLASE INHIBITORS, HAIM-I AND PAIM-I

Two proteins that act as a-amylase inhibitors, Haim I and Paim I, were crystallized and preliminary X-ray diffraction studies on them were c arried out. We also sequenced Haim I prepared from Streptomyces griseo sporeus YM-25 and confirmed that it is composed of 78 amino acid resid ues. Crystals of Haim I were grown from ammonium sulfate solution mixe d with ethanol by the vapor diffusion technique. The crystals grew as hexagonal bipyramids and diffracted X-rays beyond 2.0 angstrom resolut ion. They belong to the space group P6(1)22 (or P6(5)22) with unit cel l dimensions of a = b = 36.7 angstrom, c = 192.4 angstrom, and contain one molecule per asymmetric unit. Paim I, a protein of 39 amino acid residues produced by Streptomyces corchorusii, was crystallized under similar conditions to Haim I. The crystals diffracted X-rays beyond 2. 5 angstrom. They belong to the space group P4(1)2(1)2 (or P4(3)2(1)2) with unit cell dimensions of a = b = 65.4 angstrom, c = 96.1 angstrom, and contain three molecules per asymmetric unit.