Feng Hanqiao, Zhou Zheng, Bai Yawen
Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Building 37, Room 6114E, Bethesda, MD 20892, USA.
Proc Natl Acad Sci U S A. 2005 Apr 5;102(14):5026-31. doi: 10.1073/pnas.0501372102. Epub 2005 Mar 25.
Using native-state hydrogen-exchange-directed protein engineering and multidimensional NMR, we determined the high-resolution structure (rms deviation, 1.1 angstroms) for an intermediate of the four-helix bundle protein: Rd-apocytochrome b562. The intermediate has the N-terminal helix and a part of the C-terminal helix unfolded. In earlier studies, we also solved the structures of two other folding intermediates for the same protein: one with the N-terminal helix alone unfolded and the other with a reorganized hydrophobic core. Together, these structures provide a description of a protein folding pathway with multiple intermediates at atomic resolution. The two general features for the intermediates are (i) native-like backbone topology and (ii) nonnative side-chain interactions. These results have implications for important issues in protein folding studies, including large-scale conformation search, -value analysis, and computer simulations.
利用天然态氢交换导向的蛋白质工程和多维核磁共振技术，我们确定了四螺旋束蛋白Rd-脱辅基细胞色素b562中间体的高分辨率结构（均方根偏差为1.1埃）。该中间体的N端螺旋和C端螺旋的一部分处于未折叠状态。在早期研究中，我们还解析了同一蛋白质的另外两种折叠中间体的结构：一种是仅N端螺旋未折叠，另一种是具有重组疏水核心。这些结构共同提供了一个在原子分辨率下具有多个中间体的蛋白质折叠途径的描述。中间体的两个一般特征是：（i）类似天然的主链拓扑结构和（ii）非天然的侧链相互作用。这些结果对蛋白质折叠研究中的重要问题具有启示意义，包括大规模构象搜索、 值分析和计算机模拟。
