Faculty of Chemistry, University of Wrocław, 14 F. Joliot-Curie, Wroclaw, Poland
J Inorg Biochem. 2012 Jun;111:40-9. doi: 10.1016/j.jinorgbio.2012.02.018. Epub 2012 Mar 3.
Mononuclear and polynuclear complexes of the alloferon I with point mutation (H1K) Lys-Gly-Val-Ser-Gly-His(6)-Gly-Gln-His(9)-Gly-Val-His(12)-Gly (AlloK) and its acetylated derivative Ac-Lys-Gly-Val-Ser-Gly-His(6)-Gly-Gln-His(9)-Gly-Val-His(12)-Gly (Ac-AlloK) have been studied by potentiometric, UV-visible, CD, EPR spectroscopic and mass spectrometry (MS) methods. The high water solubility of the resulting metal complexes allowed us to obtain a complete complex speciation at different metal-to-ligand ratios ranging from 1:1 to 4:1 for AlloK while to 3:1 for Ac-AlloK. At physiological pH 7.4 and the metal-to-ligand 1:1molar ratio the AlloK peptide forms the CuL complex with the 4N {NH(2), N(-), 2N(Im)} binding mode. In the Cu(II)-AlloK 4:1 system in wide pH 6.5-10 range the Cu(4)H(-7)L complex dominates with the 3N {NH(2),2N(-)} 3×{N(Im),2N(-)} coordination mode. Imidazole nitrogen donor atoms are the primary and exclusive metal binding sites of Ac-AlloK. For Ac-AlloK and 1:1 metal-to-ligand molar ratio the CuHL complex with the 3N {3N(Im)} binding sites in pH 4.5-7.5 range is present in solution. The amine nitrogen donor and all of the histidine residues can be considered to be independent metal-binding sites in the species formed in the systems studied. As a consequence, tri- (for the Ac-AlloK) and tetra-nuclear (for the AlloK peptide) complexes for the metal-to-ligand 3:1 and 4:1molar ratios, respectively, are present in the solution.
已通过电位法、紫外可见分光光度法、圆二色光谱法、电子顺磁共振波谱法和质谱法（MS）研究了具有点突变（H1K）Lys-Gly-Val-Ser-Gly-His（6）-Gly-Gln-His（9）-Gly-Val-His（12）-Gly（AlloK）和其乙酰化衍生物 Ac-Lys-Gly-Val-Ser-Gly-His（6）-Gly-Gln-His（9）-Gly-Val-His（12）-Gly（Ac-AlloK）的单核和多核配合物。所得金属配合物的高水溶性使我们能够在不同的金属与配体比（对于 AlloK 为 1:1 至 4:1，对于 Ac-AlloK 为 3:1）下获得完整的配合物形态。在生理 pH 值 7.4 和金属与配体 1:1 的摩尔比下，AlloK 肽形成具有 4N {NH（2），N（-），2N（Im）}结合模式的 CuL 配合物。在宽 pH 值 6.5-10 范围内的 Cu（II）-AlloK 4:1 体系中，以 3N {NH（2），2N（-）} 3×{N（Im），2N（-）}配位模式占主导地位的 Cu（4）H（-7）L 配合物。咪唑氮供体原子是 Ac-AlloK 的主要和唯一的金属结合位点。对于 Ac-AlloK 和 1:1 的金属与配体摩尔比，在 pH 值 4.5-7.5 范围内存在具有 3N {3N（Im）}结合位点的 CuHL 配合物。胺氮供体和所有组氨酸残基都可以被认为是所研究体系中形成的物种中的独立金属结合位点。因此，在金属与配体比为 3:1 和 4:1 的情况下，分别在溶液中存在三核（对于 Ac-AlloK）和四核（对于 AlloK 肽）配合物。
