Molten globule of human alpha-lactalbumin: hydration, density, and compressibility of the interior.
Molten globule of human alpha-lactalbumin: hydration, density, and compressibility of the interior.
复制标题
人类 α-乳清蛋白的熔球：内部的水合、密度和可压缩性。
DOI：
10.1021/bi960264r
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发表时间：
1997
期刊：
影响因子：
2.9
通讯作者：
V. Bychkova
中科院分区：
文献类型：
--
作者：
D. P. Kharakoz;V. Bychkova
通过密度测量和超声技术测量了人α -乳清蛋白从天然到熔融的球态（酸）转变引起的比体积、部分压缩性和吸声变化，并根据蛋白质分子相变和相间水转移进行了解释。熔融球体是高度水合的状态，内部含有约270个水分子。蛋白质分子水合（膨胀）内部的本征质量密度比天然分子小5%，本征压缩系数高2倍。所得的内禀压缩率落在高伴生液体的特征值范围内。熔融球内部的水比溶剂相的体积小，可压缩性差。发现声松弛增加，表明压力依赖过程的出现。基于众所周知的体积波动与可压缩性之间的关系，计算蛋白质分子体积波动的常用方法对高度水化的熔融球状态的适用性有限，因为大部分（如果不是主要的）波动可能是由熔融球与本体溶剂之间的水交换过程决定的。
Specific partial volume, partial compressibility, and sound absorption changes induced by the native-to-molten globule state (acid) transition of the human alpha-lactalbumin were measured by means of densitometric and ultrasonic techniques and interpreted in terms of the protein molecule phase transition and interphase water transfer. The molten globule is a highly hydrated state containing about 270 water molecules inside. Intrinsic mass density of the hydrated (swollen) interior of the protein molecule is 5% smaller and the intrinsic compressibility coefficient 2 times higher than those in the native molecule. The obtained intrinsic compressibility falls into the range of values characteristic of highly associated liquids. Water inside the molten globule interior occupies less volume and is less compressible than in solvent phase. The acoustic relaxation was found to increase indicating an appearance of pressure-dependent processes. The commonly used approach to the calculation of the volume fluctuations of protein molecules, based on the well-known relation between the volume fluctuations and compressibility, is of limited applicability to the highly hydrated molten globule state because a large, if not predominant, part of the fluctuations may be determined by the process of water exchange between the molten globule and bulk solvent.