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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >An NMR study on nickel binding sites in Cap43 protein fragments
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An NMR study on nickel binding sites in Cap43 protein fragments

机译：NMR研究Cap43蛋白片段中镍结合位点

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NMR spectroscopy was used to study the interaction of Ni(II) ions with C-terminal sequence of Cap43 protein where, from Thr341 to Gly360 residue, a T1R2S3R4S5H6T7S8E9G10 ten-amino acid fragment is consecutively repeated three times. The behaviour of ends-blocked Ac-RSRSHTSEG-Am (pept1), Ac-TRSRSHTSEG-Am (pept2), and the three repeats Ac-TRSRSHTSEG-TRSRSHTSEGTRSRSHTSEG- Am (pept3) peptides towards Ni(II) ions was examined at different pH values and, for pept3, at different ligand-to-metal molar ratios. 1H-1H TOCSY, 1H-13C HSQC, 1H-1H NOESY and 1H-1H ROESY multidimensional NMR techniques were performed to understand the details of metal binding sites and the conformational behaviour of the peptides. The results confirmed that each mono-histidinic sequence of pept3 is able to independently coordinate one, two or three Ni(II) ions for 1:1, 1:2 and 1:3 ligand-to-metal molar ratios, respectively. At higher pH values, the coordination of Ni(II) involves imidazole Nd of His6 and three preceding deprotonated peptide nitrogens from the backbone, giving a {Nd, 3N-} chromophore in a square planar geometry. In addition, at lower pH values, the involvement of g-O of carboxyl group from Glu9 residue with the formation of a macrochelate giving a {Nd, g-O-, 4OH2O} chromophore in an octahedral geometry, was evidenced. NMR results allowed us to build a model for the structure of the major complex. Structural changes in the conformation of the peptide with organized Arg4 and Thr7 side chain orientation promoted by nickel coordination, were detected.
机译：NMR光谱用于研究Ni（II）离子与Cap43蛋白C端序列的相互作用，其中从Thr341到Gly360残基，一个T1R2S3R4S5H6T7S8E9G10十个氨基酸片段连续重复三次。在不同pH下检测了末端封闭的Ac-RSRSHTSEG-Am（pept1），Ac-TRSRSHTSEG-Am（pept2）和三个重复的Ac-TRSRSHTSEG-TRSRSHTSEGTRSRSHTSEGTS Am-pept3肽对Ni（II）离子的行为pept3的值，以及在不同的配体与金属的摩尔比下。进行了1H-1H TOCSY，1H-13C HSQC，1H-1H NOESY和1H-1H ROESY多维NMR技术以了解金属结合位点和肽的构象行为的详细信息。结果证实，pept3的每个单组氨酸序列能够分别配位一个，两个或三个Ni（II）离子，配体与金属的摩尔比分别为1：1、1：2和1：3。在较高的pH值下，Ni（II）的配位涉及His6的咪唑Nd和来自主链的三个先前去质子化的肽氮，从而形成方形平面几何形状的{Nd，3N-}发色团。另外，在较低的pH值下，证明了来自Glu9残基的羧基的g-O参与形成八面体几何形状的{Nd，g-O-，4OH2O}发色团的大螯合物的形成。 NMR结果使我们能够为主要络合物的结构建立模型。检测到由镍配位促进的具有组织的Arg4和Thr7侧链取向的肽构象的结构变化。

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