Yoshida S
The Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan 060.
Plant Physiol. 1984 May;75(1):38-42. doi: 10.1104/pp.75.1.38.
The thermotropic transition of plasma membrane of Dactylis glomerata was studied by using fluorescence polarization of embedded fluorophore, 1,6-diphenyl-1,3,5-hexatriene. Under the presence of 35% ethylene glycol, reversible thermotropic transitions were observed in isolated plasma membrane vesicles in nearly the same temperature range as the temperature of freezing injury to cells. In liposomes prepared from isolated plasma membranes, however, the thermotropic transitions occurred at much lower temperatures in comparison with those of intact membrane vesicles. Following treatment with pronase, the thermotropic transition also shifted downward.Thus, the thermotropic properties of plasma membranes appeared to be dependent on the membrane proteins. In vitro freezing of the isolated plasma membrane vesicles without addition of any cryoprotectant, such as sorbitol, resulted in an irreversible alteration both in the fluorescence anisotropy values and the temperatures for the thermotropic transition, suggesting an irreversible alteration in the membrane structure, presumably changes in lipid-protein interactions and protein conformation.
利用嵌入荧光团1,6 - 二苯基 - 1,3,5 - 己三烯的荧光偏振研究了鸭茅质膜的热致转变。在35%乙二醇存在下，在与细胞冻害温度几乎相同的温度范围内，在分离的质膜囊泡中观察到可逆的热致转变。然而，在由分离的质膜制备的脂质体中，热致转变发生的温度比完整膜囊泡的温度低得多。用链霉蛋白酶处理后，热致转变也向下移动。因此，质膜的热致性质似乎取决于膜蛋白。在不添加任何冷冻保护剂（如山梨醇）的情况下对分离的质膜囊泡进行体外冷冻，导致荧光各向异性值和热致转变温度都发生不可逆变化，表明膜结构发生不可逆改变，推测是脂质 - 蛋白质相互作用和蛋白质构象的变化。
