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Copper(II) Coordination Abilities of the Tau Protein's N-Terminus Peptide Fragments: A Combined Potentiometric, Spectroscopic and Mass Spectrometric Study.
ChemPlusChem ( IF 3.4 ) Pub Date : 2019-11-01 , DOI: 10.1002/cplu.201900504
Márton Lukács 1 , Györgyi Szunyog 1 , Ágnes Grenács 1 , Norbert Lihi 1, 2 , Csilla Kállay 1 , Giuseppe Di Natale 3 , Tiziana Campagna 3 , Valeria Lanza 3 , Giovanni Tabbi 3 , Giuseppe Pappalardo 3 , Imre Sóvágó 1 , Katalin Várnagy 1
Affiliation  

Copper(II) complexes of the N-terminal peptide fragments of tau protein have been studied by potentiometric and various spectroscopic techniques (UV-vis, CD, ESR and ESI-MS). The octapeptide Tau(9-16) (Ac-EVMEDHAG-NH2 ) contains the H14 residue of the native protein, while Tau(26-33) (Ac-QGGYTMHQ-NH2 ) and its mutants Tau(Q26K-Q33K) (Ac-KGGYTMHK-NH2 ) and Tau(Q26K-Y29A-Q33K) (Ac-KGGATMHK-NH2 ) include the H32 residue. To compare the binding ability of H14 and H32 in a single molecule the decapeptide Ac-EDHAGTMHQD-NH2 (Tau(12-16)(30-34)) has also been synthesized and studied. The histidyl residue is the primary metal binding site for metal ions in all the peptide models studied. In the case of Tau(9-16) the side chain carboxylate functions enhance the stability of the M-Nim coordinated complexes compared to Tau(26-33) (logK(Cu-Nim )=5.04 and 3.78, respectively). Deprotonation and metal ion coordination of amide groups occur around the physiological pH range for copper(II). The formation of the imidazole- and amide-coordinated species changes the metal ion preference and the complexes formed with the peptides containing the H32 residue predominate over those of H14 at physiological pH values (90 %-10 %) and in alkaline samples (96 %-4 %).

中文翻译:

Tau蛋白N末端肽片段的铜(II)配位能力:电位,光谱和质谱的组合研究。

tau蛋白的N末端肽片段的铜(II)配合物已通过电位分析和各种光谱技术(UV-vis,CD,ESR和ESI-MS)进行了研究。八肽Tau(9-16)(Ac-EVMEDHAG-NH2)包含天然蛋白质的H14残基,而Tau(26-33)(Ac-QGGYTMHQ-NH2)及其突变体Tau(Q26K-Q33K)(Ac- KGGYTMHK-NH2)和Tau(Q26K-Y29A-Q33K)(Ac-KGGATMHK-NH2)包括H32残基。为了比较H14和H32在单个分子中的结合能力,还合成并研究了十肽Ac-EDHAGTMHQD-NH2(Tau(12-16)(30-34))。在所有研究的肽模型中,组氨酸残基是金属离子的主要金属结合位点。与Tau(26-33)(logK(Cu-Nim)= 5.04和3.78,分别)。酰胺基团的去质子化和金属离子配位在铜(II)的生理pH范围内发生。咪唑和酰胺配位物种的形成改变了金属离子的偏好,并且在生理pH值(90%-10%)和碱性样品(96%)中,含H32残基的肽形成的络合物比H14的肽占优势-4%)。
更新日期:2019-11-14
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