title: Purification, crystallization and preliminary crystallographic analysis of AHP IX-bp, a zinc ion and pH-dependent coagulation factor IX binding protein from Agkistrodon halys Pallas venom.
abstract: A new coagulation factor IX binding protein, AHP IX-bp, has been purified from Agkistrodon halys Pallas venom and estimated to be an AB heterodimer of about 25 kDa consisting of two chains (an A chain of 15.5 kDa and a B chain of 15 kDa) linked by one or more disulfide bonds. The N-terminal sequence of AHP IX-bp has been determined and aligned with C-type lectin-like proteins. The protein has a high sequence similarity to some snake-venom C-type lectin-like proteins. AHP IX-bp binds to coagulation factor IX but not to coagulation factor X. Moreover, AHP IX-bp shows binding to coagulation factor IX in both zinc ion-dependent and pH-dependent manners. The affinity between AHP IX-bp and coagulation factor IX is higher under neutral or weakly alkaline conditions than under weakly acidic conditions. Single crystals of AHP IX-bp grown at pH 6.5 and 7.5 diffract X-rays to 2.0 and 1.8 A resolution, respectively. Both crystals are isomorphous and belong to the space group P1; only one AB heterodimer is present in the unit cell.
authors.affiliation: Key Laboratory of Structural Biology, Chinese Academy of Sciences, University of Science and Technology of China, Hefei, Anhui.
authors.forename: Jianye
authors.initials: J
authors.lastname: Zang
authors.forename: Maikun
authors.initials: M
authors.lastname: Teng
authors.forename: Liwen
authors.initials: L
authors.lastname: Niu
mesh_terms: D017836:Agkistrodon / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D003460:Crystallization; D018360:Crystallography, X-Ray; D004591:Electrophoresis, Polyacrylamide Gel; D005164:Factor IX / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D011485:Protein Binding; D012910:Snake Venoms / Q000737:chemistry*; D014757:Viper Venoms / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
chemical_list: C478742:AHP IX-bp protein, Agkistrodon halys; D012910:Snake Venoms; D014757:Viper Venoms; D005164:Factor IX; D015032:Zinc