ON THE ORIGIN OF THE ENTHALPY AND ENTROPY CONVERGENCE TEMPERATURES IN PROTEIN FOLDING
ON THE ORIGIN OF THE ENTHALPY AND ENTROPY CONVERGENCE TEMPERATURES IN PROTEIN FOLDING
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DOI：
10.1073/pnas.89.19.9335
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发表时间：
1992-10-01
影响因子：
11.1
通讯作者：
FREIRE, E
中科院分区：
文献类型：
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作者：
FU, L;FREIRE, E
细胞色素 c 折叠/展开热力学的温度依赖性已确定为中等浓度 [0-10% (vol/vol)] 甲醇的函数。展开热容变化 (DELTAC(p)) 随着甲醇浓度的增加而降低，这与较高的溶剂疏水性一致。对于给定的转变温度，这种效应会导致更高的实验焓（DELTAH 和熵 (DELTAS)）随着甲醇浓度的增加而变化。当将在不同甲醇浓度下获得的焓或熵数据集绘制为温度的函数时，可以看到它们收敛并假设 DELTAH 为 100 摄氏度左右，DELTAS 为 112 摄氏度左右为共同值。这些收敛温度与水溶液中不同蛋白质在以下情况下获得的值相似： DELTAH 和 DELTAS 相对于残基数量进行了标准化，之前假设这些收敛温度对应于 DELTAH 和 DELTAS 的疏水性贡献为零的温度；这里给出的结果与这一观点一致。
Temperature dependence of the thermodynamics of folding/unfolding for cytochrome c has been determined as a function of moderate [0-10% (vol/vol)] concentrations of methanol. Heat capacity change (DELTAC(p)) for unfolding decreases with increased concentrations of methanol, consistent with a higher solvent hydrophobicity. For a given transition temperature, this effect results in higher experimental enthalpy (DELTAH and entropy (DELTAS) changes with increased methanol concentrations. When the enthalpy or entropy data sets obtained at different methanol concentrations are plotted as a function of temperature, they are seen to converge and assume common values around 100-degrees-C for DELTAH and 112-degrees-C for DELTAS. These convergence temperatures are similar to those obtained for different proteins in aqueous solution when DELTAH and DELTAS are normalized with respect to number of residues. It has been previously hypothesized that these convergence temperatures correspond to the temperatures at which the hydrophobic contributions to DELTAH and DELTAS are zero; the results presented here agree with this viewpoint.