Zoroddu M A, Kowalik-Jankowska T, Kozlowski H, Salnikow K, Costa M
Department of Chemistry, University of Sassari, Italy.
J Inorg Biochem. 2001 Mar;84(1-2):47-54. doi: 10.1016/s0162-0134(00)00204-x.
The tetradecapeptide containing the 10 aminoacid repeated sequence on the C-terminus of the Ni(II)-induced Cap43 protein, was analyzed for Ni(II) and Cu(II) binding. A combined pH-metric and spectroscopic UV-VIS, EPR, CD and NMR study of Ni(II) and Cu(II) binding to the blocked CH3CO-Thr-Arg-Ser-Arg-Ser-His-Thr-Ser-Glu-Gly-Thr-Arg-Ser-Arg-NH2 (Ac-TRSRSHTSEGTRSR-Am) peptide, modeling a part of the C-terminal sequence of the Cap43 protein, revealed the formation of octahedral complexes involving imidazole nitrogen of histidine, at pH 5.5 and pH 7 for Cu(II) and Ni(II), respectively; a major square planar 4N-Ni(II) complex (about 100% at pH 9, log K* = -28.16) involving imidazole nitrogen of histidine and three deprotonated amide nitrogens of the backbone of the peptide was revealed; a 3N-Cu(II) complex (maximum about 70% at pH 7, log K*=-13.91) and a series of 4N-Cu(II) complexes starting at pH 5.5 (maximum about 90% at pH 8.7, log K* = -21.39 for CuH(-3)L), were revealed. This work supports the existence of a metal binding site at the COOH-terminal part of the Cap43 peptide.
对在镍（II）诱导的Cap43蛋白C末端含有10个氨基酸重复序列的十四肽进行了镍（II）和铜（II）结合分析。对镍（II）和铜（II）与封闭的CH3CO-Thr-Arg-Ser-Arg-Ser-His-Thr-Ser-Glu-Gly-Thr-Arg-Ser-Arg-NH2（Ac-TRSRSHTSEGTRSR-Am）肽（模拟Cap43蛋白C末端序列的一部分）的结合进行了pH滴定结合紫外可见光谱、电子顺磁共振、圆二色光谱和核磁共振联合研究，结果表明，在pH 5.5和pH 7时，分别形成了涉及组氨酸咪唑氮的八面体配合物，其中铜（II）和镍（II）参与；揭示了一种主要的平面四方4N-Ni（II）配合物（在pH 9时约为100%，log K* = -28.16），该配合物涉及组氨酸的咪唑氮和肽主链的三个去质子化酰胺氮；还揭示了一种3N-Cu（II）配合物（在pH 7时最大约为70%，log K*=-13.9）和一系列从pH 5.5开始的4N-Cu（II）配合物（在pH 8.7时最大约为90%，对于CuH(-3)L，log K* = -21.39）。这项工作支持了Cap43肽COOH末端部分存在金属结合位点。
