Thermodynamics and fluorescence studies of the interactions of cyclooctapeptides with Hg2+, Pb2+, and Cd2+
Thermodynamics and fluorescence studies of the interactions of cyclooctapeptides with Hg2+, Pb2+, and Cd2+
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DOI：
10.1016/j.bmc.2008.03.058
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发表时间：
2008-05-15
影响因子：
3.5
通讯作者：
Schwemlein, Stefanie
中科院分区：
文献类型：
--
作者：
Ngu-Schwemlein, Maria;Gilbert, Willie;Schwemlein, Stefanie
本工作的目的是表征环八肽（CP）含有谷氨酰和/或半胱氨酰残基与常见的重金属离子的相互作用，以促进环肽作为金属离子的传感器的设计。等温滴定量热法研究表明，含有谷氨酰和/或半胱氨酰残基的环八肽结合这些Hg 2+和Pb 2+超过Cd 2+和其他常见的金属离子。差分结合等温线，在其与Hg 2+的相互作用，支持一个两个结合位点的模型，而与Pb 2+的相关相互作用支持2：1的化学计量，这表明CP/Pb 2 +/CP模式的络合。含有谷氨酰和半胱氨酸残基的环八肽显示出对Hg 2+的显著结合亲和力（Ka = 7.6 +/- 10（7）M-1），这是由热力学和熵驱动的。这些环八肽对Hg ~（2+）的荧光猝灭作用明显强于Pd ~（2+）和Cd ~（2+）。报道了荧光强度对Hg ~（2+）和Pb ~（2+）依赖性的Stern-Volmer分析。所观察到的趋势是有用的Hg 2+传感器的设计的基础上荧光标记的cyclooctapeptides。爱思唯尔有限公司出版
The purpose of this work is to characterize the interactions of cyclooctapeptides (CP) containing glutamyl and/or cysteinyl residues with common heavy-metal ions in order to facilitate the design of cyclopeptides as sensors for metal ions. Isothermal titration calorimetry studies show that cyclooctapeptides containing glutamyl and/or cysteinyl residues bind these Hg2+ and Pb2+ over Cd2+ and other common metal ions. Differential binding isotherms, in their interactions with Hg2+, support a two-binding site model, whereas pertinent interactions with Pb2+ support a 2:1 stoichiometry, suggesting a CP/Pb2+/CP mode of complexation. The cyclooctapeptide containing both glutamyl and cysteinyl residues shows a significant binding affinity for Hg2+ (Ka = 7.6 +/- 10(7) M-1), which is both enthalpically and entropically driven. The fluorescence of these cyclooctapeptides showed pronounced fluorescence quenching responses to Hg2+ over Pd2+ and Cd2+. Stern-Volmer analyses of the dependence of fluorescence intensity on Hg2+ and Pb2+ are reported. The observed trends are useful for the design of Hg2+ sensors based on fluorophore-tagged cyclooctapeptides. Published by Elsevier Ltd.