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Structure and Fluctuation of Proteins as Revealed by Compressibility

由可压缩性揭示的蛋白质结构和波动

基本信息

批准号：
60580218
负责人：
GEKKO Kunihiko
金额：
$ 0.96万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

项目摘要

The adiabatic compressibility, <bata_s> , of 25 globular proteins in water was determined by means of sound velocity measurements at 25゜C. All the proteins studied except for subtilisin and gelain showed positive <bata_s> values, indicating the large internal compressibility of the protein molecules. The intrinsic compressibility of proteins free from the hydration effect appeared to be comparable to that of normal ice. These compressibility data were analyzed to examine the correlation of the compressibility with some structural parameters and the amino acid compositions of proteins. It was found that <bata_s> increases with increasing partial specific volume and hydrophobicity of proteins. The helix element also seemed to be a dynamic domain to increase <bata_s> . Four amino acid residues (Leu, Glu, Phe, and His) greatly increased <bata_s> , and another four (Asn, Gly, Ser, and Thr) decreased it. Some empirical equations were derived for the estimation of the <bata_s> values of unknown proteins on the basis of their amino acid compositions. The volume fluctuations of proteins revealed by the compressibility data were in the range of 30-200 ml/mol, which corresponded to about 0.3% of the total protein volume. The conformational fluctuation seemed to enhance the thermal stability of proteins. It was also found that <bata_s> increases with increasing the temperature and the glycerol concentration in solvent. These results were ascribed to dehydration of protein molecules.

在<bata_s>25 ℃下，用声速测量法测定了25种球状蛋白质在水中的绝热压缩系数。除枯草杆菌蛋白酶和明胶酶外，所有研究的蛋白质均显示<bata_s>正值，表明蛋白质分子具有较大的内部可压缩性。蛋白质的固有压缩性的水化效果似乎是正常的冰。通过对压缩性数据的分析，研究了蛋白质的压缩性与结构参数和氨基酸组成的相关性。结果表明，<bata_s>随着蛋白质的偏比容和疏水性的增加而增加。螺旋元素似乎也是一个动态的领域增加<bata_s>。其中4个氨基酸残基（Leu、Glu、Phe和His）的含量显著增加<bata_s>，另外4个氨基酸残基（Asn、Gly、Ser和Thr）的含量显著降低<bata_s>。由可压缩性数据揭示的蛋白质的体积波动在30-200 ml/mol的范围内，其对应于总蛋白质体积的约0.3%。构象波动似乎增强了蛋白质的热稳定性。实验还发现，<bata_s>随着温度的升高和甘油浓度的增加，反应速率增大。这些结果归因于蛋白质分子的脱水。