Volume changes of the molten globule transitions of horse heart ferricytochrome c: A thermodynamic cycle
Volume changes of the molten globule transitions of horse heart ferricytochrome c: A thermodynamic cycle
复制标题
马心铁细胞色素c熔球转变的体积变化：热力学循环
DOI：
10.1002/pro.5560040717
复制
发表时间：
1995
期刊：
影响因子：
8
通讯作者：
P. Kahn
中科院分区：
文献类型：
--
作者：
K. Foygel;S. Spector;Sukalyan Chatterjee;P. Kahn
测量了马心铁细胞色素c的未折叠（U）、天然（N）和熔融球（MG）构象之间的体积变化。在不存在添加的盐的情况下测定U/N（pH 2至pH 7）为-136 ± 5 mL/mol蛋白质。U至MG（pH 2，无盐至pH 2，0.5 M KCl）产生+100 ± 6 mL/mol。MG到N被分解成两个步骤，在pH 7下，通过将缓冲的KCl添加到缺乏添加的盐的缓冲蛋白质中（NClX = N与未知数目X的氯离子相互作用），N到NClX，以及通过在pH 2下在0.5M KCl中将MG跳跃到pH 7，在相同的盐浓度下，MG到NClX。N与NClX的ΔV为-30.9 ± 1.4 mL/mol蛋白，而MG与NClX的ΔV为-235 ± 6 mL/mol。在实验误差范围内，对于一个完整的热力学循环，结果之和为零。我们相信这是第一个体积循环已被测量的蛋白质的构象转变。结果进行了讨论，从蛋白质的去质子化，其他水合作用，和形成和/或扩大的包装缺陷的蛋白质的三级结构中的折叠步骤期间的水合贡献。
Volume changes among the unfolded (U), native (N), and molten globule (MG) conformations of horse heart ferricytochrome c have been measured. U to N (pH 2 to pH 7) was determined in the absence of added salt to be —136 ± 5 mL/mol protein. U to MG (pH 2, no added salt to pH 2, 0.5 M KCl) yielded +100 ± 6 mL/mol. MG to N was broken into two steps, N to NClX at pH 7 by addition of buffered KCl to buffered protein lacking added salt (NClX = N interacting with an unknown number, X, of chloride ions), and MG to NClX by jumping MG at pH 2 in 0.5 M KCl to pH 7 at the same salt concentration. The ΔV of N to NClX was —30.9 ± 1.4 mL/mol protein, whereas MG to NClX entailed a ΔV of —235 ± 6 mL/mol. Within experimental error, the results add up to zero for a complete thermodynamic cycle. We believe this to be the first volumetric cycle to have been measured for the conformational transitions of a protein. The results are discussed in terms of hydration contributions from deprotonation of the protein, other hydration effects, and the formation and/or enlargement of packing defects in the protein's tertiary structure during the steps of folding.
紫外共振拉曼光谱的细胞色素 c 结构和 Trp-59 H/D 交换的离子强度依赖性。
影响因子：
2.9
作者：
Liu,GY;Grygon,CA;Spiro,TG
通讯作者：
Spiro,TG