Kato Michiko, Hayashi Rikimaru, Tsuda Takeo, Taniguchi Kazuya
Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Japan.
Eur J Biochem. 2002 Jan;269(1):110-8. doi: 10.1046/j.0014-2956.2002.02621.x.
In order to study the pressure-induced changes of biological membrane, hydrostatic pressures of from 0.1 to 400 MPa were applied to membrane-bound Na(+)/K(+)-ATPase from pig kidney as a model system of protein and lipid membrane. The activity showed at least a three-step change induced by pressures of 0.1-100 MPa, 100-220 MPa, and 220 MPa or higher. At pressures of 100 MPa or lower a decrease in the fluidity of lipid bilayer and a reversible conformational change in transmembrane protein is induced, leading to the functional disorder of membrane-associated ATPase activity. A pressure of 100-220 MPa causes a reversible phase transition in parts of the lipid bilayer from the liquid crystalline to the gel phase and the dissociation of and/or conformational changes in the protein subunits. These changes could cause a separation of the interface between alpha and beta subunits and between protein and the lipid bilayer to create transmembrane tunnels at the interface. Tunnels would be filled with water from the aqueous environment and take up tritiated water. A pressure of 220 MPa or higher irreversibly destroys and fragments the gross membrane structure, due to protein unfolding and interface separation, which is amplified by the increased pressure. These findings provide an explanation for the high pressure-induced membrane-damage to subcellular organelles.
为了研究压力诱导的生物膜变化，将0.1至400MPa的静水压力施加于猪肾中膜结合的Na(+)/K(+)-ATP酶，作为蛋白质和脂质膜的模型系统。该活性在0.1 - 100MPa、100 - 220MPa以及220MPa及更高压力下呈现出至少三步变化。在100MPa或更低压力下，脂质双层流动性降低，跨膜蛋白发生可逆的构象变化，导致与膜相关的ATP酶活性功能紊乱。100 - 220MPa的压力会使脂质双层的部分区域发生从液晶相到凝胶相的可逆相变，以及蛋白质亚基的解离和/或构象变化。这些变化可能导致α和β亚基之间以及蛋白质与脂质双层之间的界面分离，在界面处形成跨膜通道。通道会被来自水环境的水填充并摄取氚化水。220MPa及更高的压力会由于蛋白质展开和界面分离而不可逆地破坏和破碎整个膜结构，压力增加会加剧这种破坏。这些发现为高压诱导的亚细胞器膜损伤提供了解释。
