• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemistry: A European journal >A doppel α-helix peptide fragment mimics the copper(II) interactions with the whole protein
【24h】

A doppel α-helix peptide fragment mimics the copper(II) interactions with the whole protein

机译：多普尔α-螺旋肽片段模拟铜（II）与整个蛋白质的相互作用

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The doppel protein (Dpi) is the first homologue of the prion protein (PrP~C) to be discovered; it is overexpressed in transgenic mice that lack the prion gene, resulting in neurotoxicity. The whole prion protein is able to inhibit Dpi neurotoxicity, and its N-terminal domain is the determinant part of the protein function. This region represents the main copper(II) binding site of PrP~C. Dpi is able to bind at least one copper ion, and the specific metalbinding site has been identified as the histidine residue at the beginning of the third helical region. However, a reliable characterization of copper(II) coordination features has not been reported. In a previous paper, we studied the copper(II) interaction with a peptide that encompasses only the loop region potentially involved in metal binding. Nevertheless, we did not find a complete match between the EPR spectroscopic parameters of the copper(II) complexes formed with the synthesized peptide and those reported for the copper(II) binding sites of the whole protein. Herein, the synthesis of the human Dpi peptide fragment hDpl(122-139) (Ac-KPDNKLHQQVLWRLVQEL-NH_2) and its copper(II) complex species are reported. This peptide encompasses the third a helix and part of the loop linking the second and the third helix of human doppel protein. The single-point-mutated peptide, hDpl(122-139)D124N, in which aspartate 124 replaces an asparagine residue, was also synthesized. This peptide was used to highlight the role of the carboxylate group on both the conformation preference of the Dpi fragment and its copper(II) coordination features. NMR spectroscopic measurements show that the hDpl(122-139) peptide fragment is in the prevailing ahelix conformation. It is localized within the 127-137 amino acid residue region that represents a reliable conformational mimic of the related protein domain. A comparison with the singlepoint-mutated hDpl(122-139)D124N reveals the significant role played by the aspartic residue in addressing the peptide conformation towards a helical structure. It is further confirmed by CD measurements. Potentiometric titrations were carried out in aqueous solutions to obtain the stability constant values of the species formed by copper(II) with the hDpl peptides. Spectroscopic studies (EPR, NMR, CD, UV/Vis) were performed to characterize the coordination environments of the different metal complexes. The EPR parameters of the copper(II) complexes with hDpl(122-139) match those of the previously reported copper(II) binding sites of the whole hDpl. Addition of the copper(II) ion to the peptide fragment does not alter the helical conformation of hDpl(122-139), as shown by CD spectra in the far-UV region. The aspartate-driven preorganized secondary structure is not significantly modified by the involvement of Aspl24 in the copper(II) complex species that form in the physiological pH range. To elaborate on the potential role of copper(II) in the recently reported interaction between the PrP ~C and Dpi, the affinity of the copper(II) complexes towards the prion N terminus domain and the binding site of Dpi was reported.
机译：多普勒蛋白（Dpi）是pr蛋白（PrP〜C）的第一个同源物。它在缺乏the病毒基因的转基因小鼠中过表达，导致神经毒性。整个病毒蛋白能够抑制Dpi神经毒性，其N末端结构域是蛋白功能的决定性部分。该区域代表PrP〜C的主要铜（II）结合位点。 Dpi能够结合至少一个铜离子，并且特定的金属结合位点已被确定为第三个螺旋区开始处的组氨酸残基。但是，尚未报道铜（II）配位特征的可靠表征。在先前的论文中，我们研究了铜（II）与仅包含潜在参与金属结合的环区域的肽的相互作用。然而，我们没有发现与合成肽形成的铜（II）配合物的EPR光谱参数与报道的整个蛋白质的铜（II）结合位点的EPR光谱参数完全匹配。在此，报道了人Dpi肽片段hDpl（122-139）（Ac-KPDNKLHQQVLWRLVQEL-NH_2）及其铜（II）配合物的合成。该肽包含第三个螺旋和连接人多普勒蛋白第二个和第三个螺旋的环的一部分。还合成了其中天冬氨酸124替代天冬酰胺残基的单点突变的肽hDpl（122-139）D124N。该肽被用来突出羧酸酯基团在Dpi片段的构象偏好及其铜（II）配位特征上的作用。 NMR光谱测量表明，hDpl（122-139）肽片段处于主要的螺旋结构。它位于127-137个氨基酸残基区域内，代表相关蛋白结构域的可靠构象模拟。与单点突变的hDpl（122-139）D124N的比较揭示了天冬氨酸残基在解决肽构象向螺旋结构方面的重要作用。 CD测量进一步证实了这一点。在水溶液中进行电位滴定，以获得由铜（II）与hDpl肽形成的物质的稳定常数。进行了光谱研究（EPR，NMR，CD，UV / Vis）以表征不同金属络合物的配位环境。具有hDpl（122-139）的铜（II）配合物的EPR参数与整个hDpl先前报道的铜（II）结合位点的EPR参数匹配。如远紫外区的CD光谱所示，将铜（II）离子添加至肽片段不会改变hDpl（122-139）的螺旋构象。天冬氨酸驱动的预组织二级结构没有被Aspl24参与在生理pH范围内形成的铜（II）复杂物种的显着修饰。为了详细说明铜（II）在最近报道的PrP〜C与Dpi之间的相互作用中的潜在作用，已报道了铜（II）复合物对病毒N末端结构域和Dpi的结合位点的亲和力。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号