THE HEAT-CAPACITY OF PROTEINS
THE HEAT-CAPACITY OF PROTEINS
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DOI：
10.1002/prot.340220410
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发表时间：
1995-08-01
期刊：
影响因子：
--
通讯作者：
FREIRE, E
中科院分区：
文献类型：
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作者：
GOMEZ, J;HILSER, VJ;FREIRE, E
热容量在确定蛋白质折叠和分子识别的能量方面起着重要作用。因此，更好地理解该热力学参数及其结构来源将为发展更好的分子设计策略提供新的见解。在本文中，我们分析了不同构象中蛋白质的绝对热能。这些研究的结果表明，三个主要术语解释了蛋白质的绝对热容量：（1）一个仅取决于蛋白质的主要或共价结构的术语，并包含来自拉伸和弯曲模式产生的振动频率的贡献每个价键和内部旋转的； （2）一个包含次级和第三级结构引起的非共价相互作用的贡献的术语； （3）包含水合贡献的术语。对于溶液中典型的球状蛋白，在25度C下的大部分热容量由共价结构项（接近总数的85％）给出。水合项分别贡献了约15％和40％，分别对本地和展开状态的总热量贡献。非共价结构对天然状态的总热量的贡献是正的，但很小，在25度时不超过3％。水合项（约95％）和由于非共价相互作用的丧失（最高5％）而少得多。证明可以使用单个通用数学函数来表示溶液中蛋白质的天然和展开状态的部分摩尔热容量。该功能可以通过分子量，极性溶剂和无溶剂可及表面区域以及从溶剂埋葬的总面积来实验编写。这种独特的功能准确地预测了天然和展开状态的热容量的不同幅度和温度依赖性，因此，与折叠/展开过渡相关的热容量变化的变化。 （c）1995 Wiley-Liss，Inc。
The heat capacity plays a major role in the determination of the energetics of protein folding and molecular recognition. As such, a better understanding of this thermodynamic parameter and its structural origin will provide new insights for the development of better molecular design strategies. In this paper we have analyzed the absolute heat capacity of proteins in different conformations. The results of these studies indicate that three major terms account for the absolute heat capacity of a protein: (1) one term that depends only on the primary or covalent structure of a protein and contains contributions from vibrational frequencies arising from the stretching and bending modes of each valence bond and internal rotations; (2) a term that contains the contributions of noncovalent interactions arising from secondary and tertiary structure; and (3) a term that contains the contributions of hydration. For a typical globular protein in solution the bulk of the heat capacity at 25 degrees C is given by the covalent structure term (close to 85% of the total). The hydration term contributes about 15 and 40% to the total heat capacity of the native and unfolded states, respectively. The contribution of non-covalent structure to the total heat capacity of the native state is positive but very small and does not amount to more than 3% at 25 degrees C. The change in heat capacity upon unfolding is primarily given by the increase in the hydration term (about 95%) and to a much lesser extent by the loss of noncovalent interactions (up to similar to 5%). It is demonstrated that a single universal mathematical function can be used to represent the partial molar heat capacity of the native and unfolded states of proteins in solution. This function can be experimentally written in terms of the molecular weight, the polar and apolar solvent accessible surface areas, and the total area buried from the solvent. This unique function accurately predicts the different magnitude and temperature dependences of the heat capacity of both the native and unfolded states, and therefore of the heat capacity changes associated with folding/unfolding transitions. (C) 1995 Wiley-Liss, Inc.