INRA, UMR1253 Science et Technologie du Lait et de l'Œuf, F-35042 Rennes, France.
J Phys Chem B. 2012 Sep 27;116(38):11744-53. doi: 10.1021/jp306078k. Epub 2012 Sep 14.
Understanding how proteins behave in highly concentrated systems is a major issue in many fields of research, including biology, biophysics, and chemical engineering. In this paper, we provide a comprehensive (1)H NMR study of molecular mobility in dilute to highly concentrated dispersions of the exact same protein (casein) but organized in two distinct supramolecular forms: spongelike casein micelles or soft casein aggregates. Both relaxometry and diffusometry experiments were performed, so that three different parameters are reported: spin-spin relaxation rates of non-water protons (1/T(2,ne)), spin-spin relaxation rates of water protons (1/T(2,e+w)), and water self-diffusion coefficients (D(w)). The results are discussed in an effort to understand the respective effects of protein crowding and protein supramolecular organization on each mobility indicator. We also examine if connections exist between the observed changes in molecular mobility and the already documented changes in rheological and osmotic properties of casein dispersions as concentration is increased.
在许多研究领域，包括生物学、生物物理学和化学工程，理解蛋白质在高浓度体系中的行为是一个主要问题。在本文中，我们提供了对稀至浓分散体系中（同一种）蛋白质（酪蛋白）分子迁移率的全面（1）H NMR 研究，但该体系以两种不同的超分子形式存在：海绵状酪蛋白胶束或柔软的酪蛋白聚集体。我们进行了弛豫度和扩散度实验，因此报告了三个不同的参数：非水质子的自旋-自旋弛豫率（1/T(2,ne)）、水质子的自旋-自旋弛豫率（1/T(2,e+w)）和水自扩散系数（D(w)）。我们努力讨论这些结果，以理解蛋白质拥挤和蛋白质超分子组织对每个迁移率指标的各自影响。我们还检查了在观察到的分子迁移率变化与已经记录的随着浓度增加而引起的酪蛋白分散体系流变学和渗透压性质的变化之间是否存在联系。
