液相色谱中一个新的表征参数Z Ⅳ.反相液相色谱中甲酸浓度与生物大分子的构象变化

A New Characterization Parameter Z in Liquid Chromatogaphy Ⅳ. The Relationship Between Concentration of Formic Acid and Molecular Conformation of Biopolymers in Reversed-phase Liquid Chromatography

反相高效液相色谱中蛋白质分子的Z值可以作为平衡状态下蛋白分子构象变化的表征,它与蛋白分子起始状态构象无关。在异丙醇-甲酸-水体系中蛋白的Z值会因流动相中甲酸浓度的增大而减小。除蛋白分子构象变化因素外,蛋白Z值的变化也与甲酸参与蛋白与置换剂分子间的计量置换过程有关。在蛋白分子未完全失去分子立体结构时,其Z值与分子量的立方根成正比。当甲酸浓度足够大时,例如大于40％(V/V)时,蛋白分子完全失去三维结构。

The Z value of proteins in reversed-phase high-performance liquid chromatogra-phy may be used to be a chracterization parameter of the changes in the molecular conformation at equilibrium state and it is independent of the molecular conformation of their start state. The Z values of proteins in isopropanol-formic acid-water system decrease with increasing concentration of formic acid in mobile phase. Besides molecular conformation, the change in the Z values of proteins also results from the participation of formic acid in the sto-ichiometric displacement process between protein and the displacing agent molecules. When protein molecules do not completely lose three-dimensional structure. the Z values of the proteins were found to be proportional to the cubic root of their molecular weight. When the concentration of formic acid is high enough, i.e. . >40% (V/V), protein molecules will completely lose their three-dimensional structure