Soft Metal Interactions with Sulfur Containing Biological Molecules

蛋白质和其他生物的硫化学 分子包括“软”供体基团硫醇， 硫醚和二硫化物。 这方面的具体例子 一组生物分子是抗生素， 青霉素和头孢菌素，必需的辅因子， d-生物素、免疫球蛋白如IgG和硫蛋白 如金属硫蛋白、木瓜蛋白酶和肝醇 脱氢酶。 软给体基团可使选择性复杂化 与软金属离子如Ag（I）、Cu（I）、Au（I）、Hg（II） 和Pt（II）。 这种选择性的刘易斯酸碱相互作用 提供了一种新的金属亲和性的基础 固定化软金属（ISM） 吸附作用。 ISM将补充固定化金属 亲和（IMA）色谱，IMA使用 边界硬受主，例如Cu（II）、Zn（II）和 Ni（II）与暴露的组氨酸残基相互作用 蛋白质。 中试实验证实了这一点的实用性 从稀释混合物中纯化d-生物素技术 其缺硫的生物合成前体d- 脱硫生物素 此外，金属硫蛋白被证明是 由于与下列物质络合而从溶液中除去 固定化Ag（I）离子。 有人建议，ISM 作为一种新技术进行探索，具有广泛的适用性， 生化分离 实验将提供数据 建立一个反应性模型来解释 生物化学官能团与软 金属离子 ISM还可以提供一种独特的工具， 通过使用生物缀合物的生物传感器开发 蛋白质与D-生物素。 扫描隧道显微镜 (STM)已经被用来获得第一个图像的一个 水溶液中免疫球蛋白分子。 的 Ag（I）与生物素结合物之间的相互作用 水溶液中的抗体可用于研究 免疫球蛋白结构和功能。

The sulfur chemistry of proteins and other biological molecules include the "soft" donor groups thiol, thioether, and disulfide. Specific examples of this group of biological molecules are antibiotics such as penicillin and cephalosporin, essential cofactors such as d-biotin, immunoglobins such as IgG and sulfur proteins such as metallothionein, papain, and liver alcohol dehydrogenase. Soft donor groups can complex selectivity with soft metal ions such as Ag(I), Cu(I), Au(I), Hg(II), and Pt(II). This selective Lewis acid-base interaction provides a basis for a new class of metal affinity separations named Immobilized Soft Metal (ISM) adsorption. ISM will complement Immobilized Metal Affinity (IMA) chromatography in that IMA uses borderline-hard acceptors such as Cu(II), Zn(II), and Ni(II) that interact with the exposed histidine residues of proteins. Pilot experiments have confirmed the utility of this technique in purifying d-biotin from a dilute mixture with its sulfur-deficient, biosynthetic precursor d- desthiobiotin. Also, metallothionein is shown to be removed from solution due to complexation with immobilized Ag(I) ions. It is proposed that ISM be explored as a new technique with broad applicability to biochemical separations. Experiments will provide data to establish a reactivity model explaining the interactions of biochemical functional groups with soft metal ions. ISM may also provide a unique tool for biosensor development through the use of the bioconjugate of proteins with d-biotin. Scanning Tunneling Microscopy (STM) has been used to obtain the first image of an immunoglobin molecule in aqueous solution. The interaction between Ag(I) and biotin conjugated antibodies in aqueous solution can be used to study immunoglobin structure and function through STM.