Analysis of the heat capacity dependence of protein folding.
Analysis of the heat capacity dependence of protein folding.
复制标题
蛋白质折叠的热容依赖性分析。
DOI：
10.1016/0022-2836(92)90229-d
复制
发表时间：
1992
影响因子：
5.6
通讯作者：
Honig,B
中科院分区：
文献类型：
--
作者：
Yang,AS;Sharp,KA;Honig,B
本文分析了Murphy、Privalov和Gill首次报道的25 °C下蛋白质解折叠和气体、液体和固体溶质溶解的热容量变化图。蛋白质的焓图中的负斜率被解释为与在蛋白质内部掩埋极性基团相关的大的惩罚。还讨论了伴随蛋白质在25 °C下展开的小焓变。有人认为，氢键的形成和紧密堆积的组合效应预测一个大的正的展开焓。静电计算表明，与掩埋极性基团相关的惩罚足够大，可以有效地抵消这些项，导致观察到的净焓变化很小。与蛋白质折叠的自由能的变化进行了讨论。掩埋极性基团的自由能成本在很大程度上补偿了疏水效应的稳定贡献，并且似乎可以解释蛋白质略微稳定的事实，与它们的大小和它们的相对疏水性无关。
This paper presents an analysis of plots of enthalpyversusheat capacity change at 25 °C for the unfolding of proteins and for the dissolution of gaseous, liquid and solid solutes, first reported by Murphy, Privalov & Gill. The negative slope in the enthalpy plot for proteins is interpreted as arising from a large penalty associated with burying polar groups in the protein interior. The small enthalpy changes that accompany protein unfolding at 25 °C are also discussed. It is argued that the combined effects of hydrogen bond formation and close packing predict a large positive enthalpy of unfolding. Electrostatic calculations indicate that the penalty associated with burying polar groups is large enough to effectively cancel these terms, leading to the small net enthalpy changes that are observed. The free energy changes associated with protein folding are also discussed. The free energy cost of burying polar groups largely compensates for the stabilizing contribution of the hydrophobic effect and would appear to account for the fact that proteins are marginally stable, independent of their size and of their relative hydrophobicities.