【摘要】 在pH6.30、37℃条件下,用离心超过滤法测定了11种希土离子（Ⅲ）与牛血清白蛋白（BSA）的专一性结合常数K_s和非专一性结合常数K_ns.并通过CD、UV、IR和荧光光谱研究了Tb（Ⅲ）和Eu（Ⅲ）与BSA作用的机理.结果表明,K_s和K_ns分别与希土离子（Ⅲ）和二元、一元羧酸形成配合物的稳定常数随希土系列原子序数的变化规律相一致.结合部位分布在BSA的亲水性表面,参与配位的基团只有谷氨酸、天冬氨酸残基侧链中的β、γ—COO^-和肽键中的C=O基团.根据BSA的氨基酸序列,对结合部位进行了归属.其中非专一性结合位分布于BSA分子表面的单一COO^-位置,而专一性结合位可能分别处于56-57（Asp-Glu）、170-171（Glu-Asp）,362-363（Asp-Asp）和560-561（Asp-Asp）四个位置.更多还原

【Abstract】 The binding constants of 11 tripositive lanthanide ions to bovine serum albumin(BSA) were determined at 37℃ in 50 mmol/1, pH6.30 hexamethylenetetramine buffer by the centrifugal ultrafiltration technique. It was found that the dependence of the specific binding constants(Ka) on the atomic number of lanthanide ions(ZRE) exhibits "tetrad effect", across the series. However, the variation of non-specific binding constant(Kns) with ZRE was following the pattern of the acetic-lanthanide complexes. The mechanism of the binding process was studied using CD, UV, IR and fluorescence spectroscopies. The Jesuits show that rare earths are bound to the hydrophilic surface of albumin, no considerable conformational variation of the protein after binding lanthanides, and the binding site consists of one or more carboxyl side chains whereas there is no other groups involved in such as SH and NH2. On the basis of the primary structure of BSA, it was pospulated that the four specific binding sites located on the positions of 56-57(Asp-Asp), 170-171(Glu-Asp), 362-363(Asp-Asp) and 560-561 (Asp-Asp) residues, respectively, while only the separational single Asp or Glu side chain is attributed to the non-specific binding sites.更多还原