水合醛缩酶热变性的DSC研究

本文采用差示扫描量热法(DSC),研究了水合醛缩酶在含水量h从0.08g/g至2.28g/g范围内的热变性行为。实验结果表明,当h=0.08g/g时,水合醛缩酶样品的温度扫描热谱图呈现了两个吸热峰,其中低温峰很小,高温峰很大。随着h的增大,低温峰变得更小,高温峰则出现了分峰现象。当h=0.22g/g时,低温峰消失,高温峰则分裂成了两个独立的吸热峰。随着h的继续增大,其中前峰的位置不断移向低温,直至h_0.65g/g时,才不再变化。后峰的位置则始终保持不变。当再进行第二次温度扫描时,前峰消失,而后峰却能再现。本文给出了两峰在不同含水量时的转变温度、转变焓和转变焓之和,以及它们与含水量的关系。最后,对上述诸峰的起因作了分析讨论,认为低温峰可能起因于水合醛缩酶结晶的熔化作用,前峰和后峰可能起因于醛缩酶中两种A亚基的热变性。

Study of thermal denaturation of hydrated aldolase by differential scanning calorimetry

The thermal denaturation of hydrated rabbit muscle aldolase was studied by DSC in the water content range 0.08-2.28 g water/g protein. At a water content of 0.08 g/g, 2 endothermic peaks were seen on the thermogram. The peak in the lower temperature region was very small and the peak in the higher temperature region was very large. With increasing water contents, the small peak became smaller and the large peak began to split into 2. At a water content of 0.22 g/g, the small peak disappeared and the large peak split into 2 independent peaks. With a further increase in water content, the front peak of the 2 peaks moved to low temperature, and continued until the water content was equal to 0.65 g/g. The other peak remained unchanged. The enthalpies of the 2 peaks changed with increase in water content. The small peak apparently resulted from melting of crystals of hydrated aldolase and the other 2 peaks resulted from thermal denaturation of 2 kinds of A subunits in aldolase.