• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Molecular Biology >Existence of a noncanonical state of iron-bound transferrin at endosomal pH revealed by hydrogen exchange and mass spectrometry.
【24h】

Existence of a noncanonical state of iron-bound transferrin at endosomal pH revealed by hydrogen exchange and mass spectrometry.

机译：氢交换和质谱法揭示了在内体pH值下铁结合转铁蛋白存在非规范状态。

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

Transferrin (Tf) is an enigmatic metalloprotein that exhibits a profound conformational change upon binding of ferric ion and a synergistic anion (oxalate or carbonate). While the apo and holo forms of the protein have well-defined and stable conformations termed "open" and "closed," certain aspects of Tf behavior imply the existence of alternative protein states. In this work, hydrogen/deuterium exchange was used in combination with mass spectrometry to map solvent-accessible surfaces of the iron-bound and iron-free forms of the N-terminal lobe of human serum Tf at both neutral and endosomal pH levels. While the deuterium uptake is significantly decelerated in the iron-bound state of the protein (compared with the apo form) at neutral pH, the changes are distributed very unevenly across the protein sequence. Protein segments exhibiting most noticeable gain in protection map onto the interdomain cleft region housing the iron-binding site. At the same time, protection levels of segments located in the bulk of the protein are largely unaffected by the presence of the metal. These observations are fully consistent with the notion of a metal-induced switch from the open to the closed conformation with solvent-inaccessible interdomain cleft. However, differences in the exchange behavior between the apo and holo forms of Tf become much less noticeable at endosomal pH, including the segments located in the interdomain cleft region. Intriguingly, a significant patch in the cleft region becomes slightly less protected in the presence of the metal, suggesting that the holoprotein exists in the open conformation under these slightly acidic conditions. The existence of a noncanonical state of holoTf was postulated several years ago; however, this work provides, for the first time, conclusive evidence that such alternative states are indeed populated in solution.
机译：转铁蛋白（Tf）是一种神秘的金属蛋白，在铁离子和协同阴离子（草酸盐或碳酸盐）结合后会显示出深刻的构象变化。尽管该蛋白的载脂蛋白和全脂蛋白形式具有定义明确的稳定构象，称为“开放”和“闭合”，但Tf行为的某些方面暗示着存在替代性蛋白状态。在这项工作中，氢/氘交换与质谱结合使用，绘制了中性和内体pH值下人血清Tf N端叶的铁结合型和无铁型溶剂可及表面。尽管在中性pH下，蛋白质的铁结合状态（与apo形式相比）氘的吸收显着降低，但变化在整个蛋白质序列中分布非常不均匀。在保护中表现出最明显的增益的蛋白质片段映射到容纳铁结合位点的域间裂隙区域。同时，位于大部分蛋白质中的片段的保护水平在很大程度上不受金属的存在的影响。这些观察结果与金属诱导的从开放构型向闭合构型的转变完全一致，溶剂无法进入的畴间裂隙。然而，Tf的载脂蛋白和全脂形式之间交换行为的差异在内体pH值下变得不那么明显了，包括位于域间裂隙区的片段。有趣的是，在金属的存在下，裂口区域的重要斑块受到的保护作用稍差，这表明在这些微酸性条件下，全蛋白以开放构象存在。几年前就假定存在非经典的holoTf状态。但是，这项工作首次提供了确凿的证据，证明这种替代状态确实存在于解决方案中。

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