MAD PHASING OF CORN INHIBITOR OF BLOOD COAGULATION FACTOR XIIA

我们希望使用MAD相移技术来解决晶体问题 一种特殊的蛋白酶抑制剂(CHFI)的结构 人凝血因子XIIa的选择性。第XII因子 是等离子体“接触系统”的一部分，在接触后 适当的表面，可以导致血液凝结，激活 补体系统、纤溶或炎症。它的特殊性 凝血因子XIIa的CHFI使其成为一种具有潜在重要性的有用试剂 监管任何或所有这些系统。该蛋白质含有127个 残留物，很容易结晶。我们一直在寻找重原子 用于多个同构替换阶段的导数 尝试，但我们没有发现任何有用的衍生品。分子 利用相关缓蚀剂的核磁共振结构进行替换的方法 没有成功地解决这个结构。这种蛋白质可以是 硒蛋氨酸替代物在大肠杆菌中的表达及生长 对于表达蛋白中的三种蛋氨酸。

We wish to use MAD phasing techniques to solve the crystal structure of a proteinase inhibitor (CHFI) which shows particular selectivity for the human blood coagulation Factor XIIa. Factor XII is part of the "contact system" of plasma, which after contacting appropriate surfaces, can lead to blood coagulation, activation of the complement system, fibrinolysis, or inflammation. The specificity of CHFI for factor XIIa makes it a useful reagent of potential importance in regulating any or all of these systems. The protein contains 127 residues and is readily crystallized. We have searched for heavy atom derivatives for use in multiple isomorphous replacement phasing attempts, but we have not found any useful derivatives. Molecule replacement methods using NMR structures of a related inhibitor have not been successful in solving this structure. The protein can be expressed in E. coli and grown with selenium-methionine substituting for the three methionines in the expressed protein.