Department of Biology and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, USA.
J Phys Chem B. 2010 Dec 16;114(49):16166-70. doi: 10.1021/jp106294p. Epub 2010 Sep 13.
We report the application of pressure perturbation calorimetry (PPC) to study unfolded proteins. Using PPC we have measured the temperature dependence of the thermal expansion coefficient, α(T), in the unfolded state of apocytochrome C and reduced BPTI. We have shown that α(T) is a nonlinear function and decreases with increasing temperature. The decrease is most significant in the low (2-55 °C) temperature range. We have also tested an empirical additivity approach to predict α(T) of unfolded state from the amino acid sequence using α(T) values for individual amino acids. A comparison of the experimental and calculated functions shows a very good agreement, both in absolute values of α(T) and in its temperature dependence. Such an agreement suggests the applicability of using empirical calculations to predict α(T) of any unfolded protein.
我们报告了压力微扰量热法（PPC）在研究展开蛋白中的应用。使用 PPC，我们已经测量了脱辅基细胞色素 C 和还原 BPTI 在展开状态下的热膨胀系数α（T）随温度的变化关系。我们已经表明，α（T）是一个非线性函数，并随着温度的升高而降低。这种降低在低温（2-55°C）范围内最为显著。我们还测试了一种经验加和方法，使用单个氨基酸的α（T）值，从氨基酸序列预测展开态的α（T）。实验和计算函数的比较表明，两者在α（T）的绝对值和温度依赖性方面都非常吻合。这种一致性表明，使用经验计算来预测任何展开蛋白的α（T）是可行的。
