title: Crystallization and preliminary X-ray analysis of coagulation factor IX-binding protein from habu snake venom at pH 6.5 and 4.6.
abstract: Coagulation factor IX-binding protein isolated from Trimeresurus flavoviridis (IX-bp) is a C-type lectin-like protein. It is an anticoagulant protein consisting of homologous subunits A and B. The subunits both contain a Ca2+-binding site with differing affinity (Kd values of 14 and 130 microM at pH 7.5). These binding characteristics are pH-dependent; under acidic conditions, the affinity of the low-affinity site was reduced considerably. In order to identify which site has high affinity and also to investigate the Ca2+-releasing mechanism, IX-bp was crystallized at pH 6.5 and 4.6. The crystals at pH 6.5 and 4.6 diffracted to 1.72 and 2.29 A resolution, respectively; the former crystals belong to the monoclinic space group P2(1), with unit-cell parameters a = 60.7, b = 63.5, c = 66.9 A, beta = 117.0 degrees, while the latter belong to the monoclinic space group C2, with a = 134.1, b = 37.8, c = 55.8 A, beta = 110.4 degrees.
authors.affiliation: Institute of Applied Biochemistry, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Suzuki
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Shikamoto
authors.forename: Zui
authors.initials: Z
authors.lastname: Fujimoto
authors.forename: Takashi
authors.initials: T
authors.lastname: Morita
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mizuno
mesh_terms: D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D003435:Crotalid Venoms / Q000737:chemistry*; D003460:Crystallization; D005164:Factor IX / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D021122:Protein Subunits; D030162:Reptilian Proteins / Q000737:chemistry*; D017841:Trimeresurus; D014961:X-Ray Diffraction
chemical_list: D003435:Crotalid Venoms; D021122:Protein Subunits; D030162:Reptilian Proteins; C109516:factor IX-binding protein, Trimeresurus flavoviridis; D005164:Factor IX; D002118:Calcium