Communication of stabilizing energy between substructures of a protein.
Communication of stabilizing energy between substructures of a protein.
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蛋白质亚结构之间稳定能量的交流。
DOI：
10.1021/bi048141r
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Bowler,BruceE
中科院分区：
文献类型：
--
作者：
Kristinsson,Richard;Bowler,BruceE
通过确定细胞色素的最不稳定的 N 黄色亚结构、第二不稳定的红色亚结构和最稳定的蓝色亚结构中 52 位突变的稳定作用，研究了蛋白质亚结构之间的热力学通讯。 iso-1-细胞色素c 的 Lys 73 → His (H73) 变体含有这些突变，用于通过 His 73 介导的碱性构象转变的 pH 和盐酸胍 (gdnHCl) 依赖性来测量细胞色素红色亚结构的稳定性。 Blue 子结构的稳定性通过 gdnHCl 的整体去折叠来测量，并且与 H73 变体相比增加了 1 至 3.5 kcal/mol。数据表明，红色亚结构稳定性的增加与整体稳定性的增加类似，与稳定能量从较少（N-黄色）到更稳定（红色和蓝色）蛋白质亚结构的向上传播一致。该结果还支持细胞色素的 N 黄色和红色亚结构是顺序展开的，而不是独立展开的。数据表明，52 位的亮氨酸改变了红色亚结构部分展开的性质，这对于单位点突变来说是一个令人惊讶的效果。对于所有变体，Lys 79 碱性状态形成的热力学（不展开整个红色子结构）显示，相对于蓝色子结构的稳定性，展开的蛋白质部分的稳定性较低，这表明当展开不对应于天然子结构时，子结构之间的能量传播受到一定程度的破坏。
Thermodynamic communication between protein substructures has been investigated by determining the stabilizing effect of mutations at position 52 in the least stable, N-yellow, substructure of cytochromecon the second least stable, Red, and most stable, Blue, substructures of the protein. A Lys 73 → His (H73) variant of iso-1-cytochromec, containing these mutations was used to measure the stability of the Red substructure of cytochromecthrough the pH and guanidine hydrochloride (gdnHCl) dependence of the His 73-mediated alkaline conformational transition. The stability of the Blue substructure was measured by global unfolding with gdnHCl and increased by 1 to 3.5 kcal/mol versus the H73 variant. The data demonstrate that the increase in stability of the Red substructure is similar to the increase in global stability, consistent with upward propagation of stabilizing energy from less (N-yellow) to more stable (Red and Blue) protein substructures. The result also supports sequential rather than independent unfolding of the N-yellow and Red substructures of cytochromec. The data indicate that a leucine at position 52 alters the nature of partial unfolding of the Red substructure, a surprising effect for a single-site mutation. For all variants, the thermodynamics of formation of the Lys 79 alkaline state, which does not unfold the entire Red substructure, shows less stabilization of the portion of the protein unfolded relative to the stabilization of the Blue substructure, indicating that propagation of energy between substructures is somewhat disrupted when unfolding does not correspond to a natural substructure.