Co(II) electronic configuration allows its use as a spectroscopic probe in UV-Vis experiments to characterize the metal coordination sphere that is an essential component of the functional structure of zinc-binding proteins and to evaluate the metal ion affinities of these proteins. Here, exploiting the capability of the prokaryotic zinc finger to use different combinations of residues to properly coordinate the structural metal ion, we provide the UV-Vis characterization of Co(II) addition to Ros87 and its mutant Ros87_C27D which bears an unusual CysAspHis₂ coordination sphere. Zinc finger sites containing only one cysteine have been infrequently characterized. We show for the CysAspHis₂ coordination an intense d-d transition band, blue-shifted with respect to the Cys₂His₂ sphere. These data complemented by NMR and CD data demonstrate that the tetrahedral geometry of the metal site is retained also in the case of a single-cysteine coordination sphere.

中文翻译：

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紫外可见光谱揭示的原核锌指结构域中的Co（II）配位。

Co（II）电子构型允许其在UV-Vis实验中用作光谱探针，以表征作为锌结合蛋白功能结构必不可少的成分的金属配位球，并评估这些蛋白的金属离子亲和力。在这里，我们利用原核锌指使用残基的不同组合来适当协调结构金属离子的能力，提供了对Ros87及其突变体Ros87_C27D除具有异常CysAspHis ₂配位以外的Co（II）的UV-Vis表征领域。仅包含一个半胱氨酸的锌指位点很少得到表征。我们为CysAspHis ₂协调显示了强烈的d - d过渡带，相对于Cys ₂ His ₂球体发生了蓝移。这些由NMR和CD数据补充的数据表明，在单半胱氨酸配位球的情况下，也保留了金属位点的四面体几何形状。