LIGAND VARIATION AND METAL-ION BINDING-SPECIFICITY IN ZINC FINGER PEPTIDES
LIGAND VARIATION AND METAL-ION BINDING-SPECIFICITY IN ZINC FINGER PEPTIDES
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DOI：
10.1021/ic00058a030
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发表时间：
1993-03-17
影响因子：
4.6
通讯作者：
BERG, JM
中科院分区：
文献类型：
--
作者：
KRIZEK, BA;MERKLE, DL;BERG, JM
制备了三种具有配位位点CYS2HiS2、CYS3His和CYS4的金属结合肽，并对其金属结合特性进行了表征。肽基于锌指一致序列，序列为ProTyrLysCys4ProGluCys7GlyLysSerPheSerGlnysSerAspLeuValLysXaa20GhiArgTbrYaa24ThrGly （Xaa = Yaa = His; Xaa = His, Yaa = Cys; Xaa = Yaa = Cys）。通过一系列直接和竞争金属离子滴定法测定了与Co2+、Zn2+和Cd2+的肽配合物的解离常数。当咪唑配体被硫代酸盐取代时，配体场稳定能的降低可以半定量地解释肽对Co2+相对于Zn2+的亲和趋势。对Cd2+的亲和力增加超过两个数量级的每一个硫代盐取代咪唑，以保持硬-软酸碱效应。此外，研究结果表明，N2S2配位位点在研究的位点中是独一无二的，它允许Zn2+对第一行过渡金属和第二行元素（如Cd2+）有明显的优先结合。
Three metal binding peptides with coordination sites CYS2HiS2, CYS3His, and CYS4 have been prepared and their metal binding properties characterized. The peptides are based on a zinc finger consensus sequence and have the sequences ProTyrLysCys4ProGluCys7GlyLysSerPheSerGlnysSerAspLeuValLysXaa20GhiArgTbrYaa24ThrGly (Xaa = Yaa = His; Xaa = His, Yaa = Cys; Xaa = Yaa = Cys). The dissociation constants for the peptide complexes with Co2+, Zn2+, and Cd2+ have been determined via a series of direct and competitive metal ion titrations. The trend in relative affinities of the peptides for Co2+ over Zn2+ can be semiquantitatively accounted for by the decrease in ligand field stabilization energy as imidazole ligands are replaced by thiolates. The affinity for Cd2+ increases by over two orders of magnitude for each thiolate for imidazole substitution, in keeping with hard-soft acid-base effects. Furthermore, the results reveal that the N2S2 coordination site is unique among the sites studied in allowing significant preferential binding of Zn2+ over both first row transition metals and second row elements such as Cd2+.