一个不寻常的Co-S键连接了B12伴侣在一个蛋白间复合体中的伴侣
Romila Mascarenhas1, Markus Ruetz1, Natalie Heitman1
1Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109.
概括
人类B12陪伴者MMACHC和MMADHC通过硫键形成一个独特的复合体,在运输过程中保护维生素B12. 这个结构揭示了细胞如何管理这种必不可少的辅助因子.
科学领域:
- 生物化学 生物化学
- 结构生物学 结构生物学
- 分子生物学分子生物学
背景情况:
- 陪伴者对于特定的过渡金属负载和预防细胞通路中的副作用反应至关重要.
- 维生素B12 (科巴胺) 是人类必需的辅助因子,由于其复杂的结构,需要特定的转位机制.
研究的目的:
- 为了确定人类MMACHC和MMADHC B12伴侣的晶体结构.
- 阐明由这些陪伴者介导的B12转移和保护机制.
主要方法:
- 在3.4 Å分辨率的X射线晶体学.
- 对蛋白际复合体结构和B12结合部位的分析.
主要成果:
- 晶体结构显示MMACHC和MMADHC由共价-硫键连接在一起.
- 维生素B12在基离状态下与MMACHC结合,MMADHC提供了一个轴联体.
- 该复合物防止了B12衍生物的自发分解,这表明它具有保护作用.
结论:
- 在MMACHC和MMADHC之间形成高亲和复合体时,共价-硫键是必不可少的.
- 蛋白间复合体可能有助于B12从伴侣体中脱离.
- 接口与已知的临床变异无关,突出显示了-硫键的重要性.
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