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首页> 外文期刊>Cell biology international. >A MECHANISTIC VIEW OF THE NON-IDEAL OSMOTIC AND MOTIONAL BEHAVIOR OF INTRACELLULAR WATER
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A MECHANISTIC VIEW OF THE NON-IDEAL OSMOTIC AND MOTIONAL BEHAVIOR OF INTRACELLULAR WATER

机译：鞘内水非理想渗透和运动行为的力学观点

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It is commonly assumed that essentially all of the water in cells has the same ideal motional and colligative properties as does water in bulk liquid state. This assumption is used in studies of volume regulation, transmembrane movement of solutes and electrical potentials, solute and solution motion, solute solubility and other phenomena. To get at the extent and the source of non-ideally behaved water (an operational term dependent on the measurement method), we studied the motional and colligative properties of water in cells, in solutions of amino acids and glycine peptides whose surface characteristics are known, and in solution of bovine serum albumin, hemoglobin and some synthetic polypeptides. Solutions of individual amino acids with progressively larger hydrophobic side chains showed one perturbed water molecule (structured-slowed in motion) per nine square angstroms of hydrophobic surface area. Water molecules adjacent to hydrophobic surfaces form pentagonal structural arrays, as shown by X-ray diffraction studies, that are reported to be disrupted by heat, electric held, hydrostatic pressure and phosphorylation state. Hydrophilic amino acids demonstrated water destructuring (increased motion) that was attributed to dielectric realignment of dipolar water molecules in the electric field between charge groups. In solutions of proteins, several methods indicate the equivalent of 2-8 layers of structured water molecules extending beyond the protein surface, and we have recently demonstrated that induced protein conformational change modifies the extent of non-ideally behaved water. Water self-diffusion rate as measured in three different cell types was about half that of bulk water, indicating that most of the water in these cells was slower in motion than bulk water. In different cell types the extent of osmotically perturbed water ranged from less than half to almost all of the intracellular water. The assumption that essentially all intracellular water has ideal osmotic and motional behavior is not supported by the experimental findings. The non-ideality of cell water is an operational term. Therefore, the amount of non-ideally behaving water is dependent on the characteristics of water targeted, i.e. the measurement method, and a large fraction of it is explainable in mechanistic terms at a molecular level based on solute-solvent interactions. (C) 1997 Academic Press Limited. [References: 46]
机译：通常认为，基本上所有细胞中的水与散装液态水具有相同的理想运动和依数性质。该假设用于体积调节，溶质的跨膜运动和电势，溶质和溶液运动，溶质溶解度和其他现象的研究。为了了解不理想行为的水的程度和来源（一个操作术语取决于测量方法），我们研究了在已知表面特性的氨基酸和甘氨酸肽溶液中细胞中水的运动和依数性质。 ，以及在牛血清白蛋白，血红蛋白和某些合成多肽的溶液中。具有逐渐增大的疏水侧链的单个氨基酸的溶液显示每九平方毫米的疏水表面积有一个扰动的水分子（运动缓慢）。 X射线衍射研究表明，与疏水表面相邻的水分子形成五边形结构阵列，据报道，这些分子被热，电保持，静水压力和磷酸化状态破坏。亲水性氨基酸显示出水破坏（运动增加），这归因于电荷基团之间的电场中偶极水分子的介电重新排列。在蛋白质溶液中，有几种方法表明等效的2-8层结构化水分子延伸超出了蛋白质表面，并且我们最近证明，诱导的蛋白质构象变化会改变非理想行为的程度。在三种不同的细胞类型中测得的水自扩散速率约为散装水的一半，这表明这些细胞中的大多数水运动比散装水慢。在不同的细胞类型中，渗透扰动的水量范围从不到细胞内水的一半到几乎全部。实验结果不支持基本所有细胞内水具有理想的渗透和运动行为的假设。细胞水的不理想是一个可操作的术语。因此，非理想行为的水量取决于目标水的特性，即测量方法，并且其中很大一部分可以基于溶质-溶剂相互作用在分子水平上用机械学的方式解释。 （C）1997 Academic Press Limited。 [参考：46]

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