Structure and Fluctuation of Proteins as Revealed by Compressibility

《糖尿病并发症》<bata_s>，水中25种全球蛋白是根据25 ° C的声音流速测量方法确定的。所有研究的蛋白质都是亚替林和凝胶显示出的积极<bata_s>价值观的，并表明蛋白质分子的较大内部复杂性。蛋白质的内在复杂性，不受水化效应的影响，可以与正常的冰相比。这些复杂性数据已被分析，以测试与某些结构参数和氨基酸组合物的复杂性的相关性。这是发现<bata_s>的，因为增加了部分特定体积和蛋白质的羟基含量。螺旋元素似乎也是一个动态域，可以增加<bata_s>。四种氨基酸溶液（Leu， Glu， Phe， and His）极大地增加<bata_s>，以及其他四种（Asn， Gly， Ser， and Thr）分解。一些经验方程被衍生出用于估计值<bata_s>的未知蛋白质在他们的氨基酸组合物基础上。根据复杂性数据在30-200毫升/摩尔的范围内揭示的蛋白质体积，对应于蛋白质总体积的0.3%。“构象流动”似乎是为了增强蛋白质的热稳定性。它还<bata_s>发现了一种增加的现象，即温度增加和糖醇浓度在溶剂中的增加。这些结果被归类为蛋白质分子的脱水。

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.