摘要
用荧光及园二色谱对人红细胞收缩蛋白（ＳＰ）与不同组成和构型的Ｐｔ（Ｉ）络合物的作用进行了研究。结果表明，ＳＰ有４７×１０２个顺铂（ＣＤＤＰ）结合部位。其中，最高亲和性部位７０个，Ｋ１＞３４７×１０６；较高亲和性的１８×１０２个，其Ｋ２＝３４７×１０６；其余２２×１０２个为低亲和性的，其Ｋ３＝８７７×１０５。Ｐｔ（Ｉ）络合物与ＳＰ的结合导致ＳＰ构象变化，这种变化与Ｐｔ（Ｉ）络合物浓度及络合物与ＳＰ的浓度比有关。ＣＤＤＰ及顺式二水二氨合铂（Ｉ）与ＳＰ的作用在初始１ｈ内遵从双阶段一级动力学，动力学常数也已测定。反应１ｈ后，为络合物与ＳＰ作用的后续变化阶段，这一阶段可能涉及ＳＰ的构象改变、聚合及解聚。值得注意的是，ＳＰ与１，２环己二胺不同异构体作为载体配体的Ｐｔ（Ｉ）络合物作用时，空间匹配性比Ｐｔ（Ｉ）与ＳＰ的巯基的亲和性显得更为重要。
The interactions between human erythrocyte spectrin(SP) and Pt(II) complexes with different composition and configuration were studied by fluorescence and circular dichroism spectra. The results showed that there are 4.7×10 2 binding sites of cisplatin(CDDP) in a spectrin tetramer(SPT). Among them, about 70 sites with apparent binding constant K 1>3.47×10 6 were of highest affinity, 1.8×10 2 sites with K 2 = 3.47×10 6 were of high affinity, and other 2.2×10 2 sites with K 3 = 8.77×10 5 were of low affinity. The conformation change of spectrin, depending on the concentration of Pt(II) complex and molar ratio(R) of Pt(II) complex to spectrin, was induced by the binding of Pt(II) complexes. It indicated that the interaction of both CDDP and cis diaquodiamine platinum(DADP) with SP followed a two step first order kinetic process in the first stage (1 h), and the kinetic constants were determined. In the second stage, the induced conformation change, polymerization and depolymerization of SP were probably involved. It was noticed that in the reaction of SP and Pt(II) complexes with 1,2 cyclohexanediammine isomers as chiral carrier ligand, stereo matching played a more important role than the affinity of Pt(II) to thiol groups of SP.
