Hydration state change of proteins upon unfolding in sugar solutions
Hydration state change of proteins upon unfolding in sugar solutions
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DOI：
10.1016/j.bbapap.2007.05.008
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发表时间：
2007-07-01
影响因子：
3.2
通讯作者：
Miyawaki, Osato
中科院分区：
文献类型：
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作者：
Miyawaki, Osato
通过分析蛋白质在各种糖溶液中的热去折叠行为，获得了去折叠时蛋白质水合数的变化An，其中水活度a（w）是变化的。通过应用Wyman-Tanford方程的倒数形式，在pH=5.5、4.2和2.8时，核糖核酸酶A的An分别为133.9、124.1和139.2/蛋白质分子，在pH=5.5时，溶菌酶的An为201.4，在pH=2.0时，α-凝乳酶原A的An为100.1/蛋白质分子。在所测试的糖中，还原糖与非还原糖相比给出了较低的表观An，这可能是因为在高温下还原末端与蛋白质的氨基直接相互作用。基于An的知识，提出了一个新的蛋白质稳定性的热力学模型，该模型考虑了蛋白质在去折叠过程中水合状态的变化。从这个模型中，aw的贡献被证明总是积极的蛋白质的稳定和它的效果是不可忽略的依赖于Δ n和a（w）。(c)2007 Elsevier B. V.保留所有权利。
Change in hydration number of proteins upon unfolding, An, was obtained from the analysis of thermal unfolding behavior of proteins in various sugar solutions with water activity, a(w), varied. By applying the reciprocal form of Wyman-Tanford equation, An was determined to be 133.9, 124.1, and 139.2 per protein molecule for ribonuclease A at pH=5.5, 4.2, and 2.8, respectively, 201.4 for lysozyme at pH=5.5, and 100.1 for alpha-chymotripnogen A at pH=2.0. Among the sugars tested, reducing sugars gave the lower apparent An as compared with nonreducing sugars probably because of the direct interaction of reducing terminal with amino group of proteins at a high temperature. From the knowledge of An, a new thermodynamic model for protein stability was proposed with explicit consideration for hydration state change of protein upon unfolding. From this model, the contribution of aw was proven to be always positive for stabilization of proteins and its effect is not negligible depending on Delta n and a(w). (c) 2007 Elsevier B.V. All rights reserved.