ROLE OF THE HYDROPHOBIC EFFECT IN STABILITY OF SITE-SPECIFIC PROTEIN-DNA COMPLEXES
ROLE OF THE HYDROPHOBIC EFFECT IN STABILITY OF SITE-SPECIFIC PROTEIN-DNA COMPLEXES
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DOI：
10.1016/0022-2836(89)90608-6
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发表时间：
1989-10-20
影响因子：
5.6
通讯作者：
RECORD, MT
中科院分区：
文献类型：
--
作者：
HA, JH;SPOLAR, RS;RECORD, MT
Lac抑制子与对称操纵子序列的结合和EcoRI内切酶与其特定识别位点的结合都表现出平衡结合常数(Kobs)对温度的特征依赖关系，其中Kobs在生理相关的温度范围内达到相对最大。这种行为似乎对特定部位的蛋白质-DNA相互作用非常普遍，表明在结合过程中有很大的负标准热容变化(ΔCP，obS0)。通过与模型化合物转移研究和蛋白质折叠数据的类比，我们认为这主要是在缔合过程中从水中去除非极性表面的结果。从ΔCP，OBS0，我们获得关于暴露在水中的非极性表面积(ΔAnp)的变化和相应的疏水缔合驱动力(ΔGhyd0)的半定量信息：ΔGhyd0simeq。8(.+-.1).时代。101.DELTA CP，ob0.simeq.-22(.+-.5)DELTA和我们认为，水中非极性表面的去除(疏水效应)和阳离子的释放(聚电解质效应)驱动了热力学上不利的过程(例如构象扭曲)，这是在特定络合物中实现相互补充的识别表面(在空间和官能团水平上)所必需的。
The site-specific binding interaction of lac repressor with a symmetric operator sequence and of EcoRI endonuclease with its specific recognition site both exhibit a characteristic dependence of equilibrium binding constant (Kobs) on temperature, in which Kobs attains a relative maximum in the physiologically relevant temperature range. This behaviour, which appears to be quite general for site-specific protein-DNA interactions, is indicative of a large negative standard heat capacity change (.DELTA.CP,obs0) in the association process. By analogy with model compound transfer studies and protein folding data, we propose that this .DELTA.CP,obs0 results primarily from the removal of non-polar surface from water in the association process. From .DELTA.CP,obs0 we obtain semiquantitative information regarding the change in water-exposed non-polar surface area (.DELTA.Anp) and the corresponding hydrophobic driving force for association (.DELTA.Ghyd0):.DELTA.Ghyd0 .simeq. 8(.+-. 1) .times. 101 .DELTA.CP,obs0 .simeq. -22 (.+-. 5) .DELTA.Anp. We propose that removal of non-polar surface from water (the hydrophobic effect) and release of cations (the polyelectrolyte effect) drive the thermodynamically unfavorable processes (e.g. conformational distortions) necessary to achieve mutually complementary recognition surfaces (at a steric and functional-group level) in the specific complex.