Minton A P
Laboratory of Biochemical Pharmacology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
Biophys J. 1992 Oct;63(4):1090-100. doi: 10.1016/S0006-3495(92)81663-6.
The confinement of macromolecules within enclosures or "pores" of comparable dimensions results in significant size- and shape-dependent alterations of macromolecular chemical potential and reactivity. Calculations of the magnitude of this effect for model particles of different shapes in model enclosures of different shapes were carried out using hard particle partition theory developed by Giddings et al. (J. Phys. Chem. 1968. 72:4397-4408). Results obtained indicate that the equilibrium constants of reactions, such as isomerization, self-association, and site binding, that result in significant change in macromolecular size, shape, and/or mobility may be altered within pores by as much as several orders of magnitude relative to the value in the unbounded or bulk phase. Confinement also produces a substantial size-dependent outward force on the walls of an enclosure. These results are likely to be important within the fluid phase of biological media, such as the cytoplasm of eukaryotic cells, containing significant volume fractions of large fibrous structures (e.g., the cytomatrix).
将大分子限制在尺寸相当的封闭空间或“孔”内，会导致大分子化学势和反应性在大小和形状上发生显著变化。利用吉丁斯等人（《物理化学杂志》，1968年，72卷：4397 - 4408页）提出的硬粒子分配理论，对不同形状的模型封闭空间中不同形状的模型粒子的这种效应大小进行了计算。所得结果表明，诸如异构化、自缔合和位点结合等导致大分子大小、形状和/或迁移率发生显著变化的反应的平衡常数，在孔内相对于无界或本体相中的值可能会改变几个数量级。限制还会在封闭空间壁上产生显著的尺寸依赖性外向力。这些结果在生物介质的流体相中可能很重要，例如真核细胞的细胞质，其中含有大量体积分数的大型纤维结构（如细胞基质）。
