Di Natale Giuseppe, Damante Chiara A, Nagy Zoltán, Osz Katalin, Pappalardo Giuseppe, Rizzarelli Enrico, Sóvágó Imre
Department of Chemical Sciences, University of Catania V.le A. Doria 6, 95125 Catania, Italy.
J Inorg Biochem. 2008 Nov;102(11):2012-9. doi: 10.1016/j.jinorgbio.2008.07.017. Epub 2008 Aug 8.
The solution conformation and the copper(II) binding properties have comparatively been investigated for the two novel hexapeptides Ac-HPSGHA-NH(2) (P2) and Ac-HGSPHA-NH(2) (P4). The study has been carried out by means of CD, NMR, EPR and UV-Vis spectroscopic techniques in addition to potentiometric measurements to determine the stability constants of the different copper(II) complex species formed in the pH range 3-11. The peptides contain two histidine residues as anchor sites for the metal ion and differ only for the exchanged position of the proline residue with glycine. CD and NMR results for the uncomplexed peptide ligands suggest a predominantly unstructured peptide chain in aqueous solution. Potentiometric and spectroscopic data (UV-Vis, CD and EPR) show that both peptides strongly interact with copper(II) ions by forming complexes with identical stoichiometries but different structures. Furthermore, Far-UV CD experiments indicate that the conformation of the peptides is dramatically affected following copper(II) complexation with the P4 peptide adopting a beta-turn-like conformation.
已对两种新型六肽Ac-HPSGHA-NH₂（P2）和Ac-HGSPHA-NH₂（P4）的溶液构象和铜（II）结合特性进行了比较研究。除了电位滴定测量以确定在3-11 pH范围内形成的不同铜（II）络合物物种的稳定常数外，还通过圆二色光谱（CD）、核磁共振（NMR）、电子顺磁共振（EPR）和紫外可见光谱（UV-Vis）技术开展了这项研究。这些肽含有两个组氨酸残基作为金属离子的锚定位点，仅脯氨酸残基与甘氨酸的交换位置不同。未络合肽配体的CD和NMR结果表明，在水溶液中肽链主要为无规结构。电位滴定和光谱数据（UV-Vis、CD和EPR）表明，两种肽都通过形成具有相同化学计量比但结构不同的络合物与铜（II）离子强烈相互作用。此外，远紫外CD实验表明，与铜（II）络合后，肽的构象受到显著影响，P4肽呈现出类似β-转角的构象。
