Abstract Density as a function of temperature is determined for a set of α-chymotrypsin and bovine serum albumin solutions in pure water both in the native and the degraded state, the latter achieved by heating them above the denaturation temperature. This allows the temperature of maximum density (TMD) to be obtained against composition. Partial molar volume at infinite dilution of the protein is also calculated. Thermodynamic consistency between composition dependence of TMD and temperature dependence of partial volume is checked, obtaining satisfactory results. TMD behaviour against mass fraction for both native proteins is very similar, but important differences between native and degraded states, and also between the degraded forms of both proteins are found. These results show, for the first time, the strong effects that protein degradation have over the TMD of aqueous solutions, and therefore, over the microscopic structure of water.

中文翻译：

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水中蛋白质最大密度的温度：α-胰凝乳蛋白酶和牛血清白蛋白

摘要 密度与温度的函数关系是由一组 α-胰凝乳蛋白酶和牛血清白蛋白溶液在纯水中以天然和降解状态确定的，后者是通过将它们加热到变性温度以上来实现的。这允许根据成分获得最大密度 (TMD) 的温度。还计算了蛋白质无限稀释时的部分摩尔体积。检查了 TMD 的成分依赖性和部分体积的温度依赖性之间的热力学一致性，获得了满意的结果。两种天然蛋白质对质量分数的 TMD 行为非常相似，但发现了天然和降解状态之间以及两种蛋白质的降解形式之间的重要差异。这些结果首次表明，