Thermodynamic stability of the C-terminal domain of the human inducible heat shock protein 70
Thermodynamic stability of the C-terminal domain of the human inducible heat shock protein 70
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DOI：
10.1016/j.bbapap.2003.12.007
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发表时间：
2004-06-01
影响因子：
3.2
通讯作者：
Alonso, C
中科院分区：
文献类型：
--
作者：
Fuertes, MA;Pérez, JM;Alonso, C
结合光谱法和量热法研究了人诱导型热休克蛋白70底物结合区的稳定性。蛋白质的热变性涉及四种可接近的状态：天然状态、两种大量存在的中间体和变性状态，在pH 6.5下，其转变温度分别为52.8、56.2和71.2 ℃。中间光谱性质类似于熔融球，但它们仍然保留了大量的焓和热容量的展开。此外，第一中间体和天然状态的类似热容量表明中间体的疏水核心将是高度天然样的，并且其形成将涉及结构的局部部分中的增加的无序，而不是全局无序状态的形成。Hsp 70的C-末端的结构随着pH从中性分离而不稳定。中间体在酸性和碱性pH的热冲击条件下聚集。氯化胍变性也表明，蛋白质经历了一个顺序的去折叠过程。在20 ℃（pH 6.5）下与二级结构损失相关的自由能变化为3.1 kcal（.）mol（-1）。这些值同意从差示扫描量热法估计的第二中间体和最终变性状态之间的过渡的自由能变化。(C)2004 Elsevier B. V.保留所有权利。
The stability of the substrate-binding region of human inducible Hsp70 was studied by a combination of spectroscopic and calorimetric methods. Thermal denaturation of the protein involves four accessible states: the native state, two largely populated intermediates, and the denatured state, with transition temperatures of 52.8, 56.2 and 71.2 degreesC, respectively, at pH 6.5. The intermediate spectroscopic properties resemble those of molten globules but they still retain substantial enthalpy and heat capacity of unfolding. Moreover, the similar heat capacities of the first intermediate and the native state suggests that the hydrophobic core of the intermediate would be highly native-like and that its formation would involve an increased disorder in localized portions of the structure rather than formation of a globally disordered state. The structure of the C-terminal of Hsp70 is destabilized as the pH separates from neutrality. The intermediates become populated under heat shock conditions at acidic and basic pHs. Denaturation by guanidine chloride also indicated that the protein undergoes a sequential unfolding process. The free energy change associated to the loss of secondary structure at 20 degreesC (pH 6.5) is 3.1 kcal(.)mol(-1) at high salt conditions. These values agree with the free energy changes estimated from differential scanning calorimetry for the transition between the second intermediate and the final denatured state. (C) 2004 Elsevier B.V. All rights reserved.