【摘要】 本文首次用DSC研究水合紫膜的热力学性质了,实验发现室温至400K内紫膜有三个吸热峰.水合对紫膜特别是其中蛋白质的结构及结构转变有很大影响.在R≌O.05时,BR变性峰才变得更为明显,其焓值也开始由大到小变化.在R≌O.09处,转变峰Ⅰ消失.在R=0.17处,BR变性峰的焓值及半宽分别达到其稳定值和最小值,△H=2.82±0.18 cal/gPM和△T_1/2=5.88K.在R≌0.25处,开始出现反映BR三、四级结构变化及紫膜晶格转化的峰Ⅱ.在R≌0.40处,变性峰半宽及峰温分别达到其稳定值△T_1/2=9.20±0.62K和T₃=373.1±0.46K.更多还原

【Abstract】 The thermal transitions of hydrated purple membrane were studied by differential scanning calorimatry (DSC). Three endothermic peaks were observed in the temperature range from room temperature to 400K. Hydration has a great influence on the structure of purple membrane, the conformation of bacteriorhodopsin and their transitions. The denaturation peak of bacteriorhodopsin becomes more obvious at about R≈0.05, when the enthalpy of the peak drops with further hydration. Peak I disappears at R≈0.09. At about R=0.17, the enthalpy and half width of the denaturation peak reach their steady values ΔH =2.82 ±0.18 cal/gPM and ΔT1/2 =5.88K respectively. Peak II, which involves the transition that relates to tertiary and quaternary structure of bacteriorhodopsin and a cooperative change in the crystal lattice, is observed in the region R ≥ 0.25, at about 350K The half width and temperature of the denaturation peak remain constants, ΔT1/2=9.20±0.62K and T3 = 373.1±0.46K, respectively, when the water content is no less than 0.40.更多还原