Abstract
In the past few years, many measurement methods have been used to study the structural change of protein after heating, such as differential scanning method,circularly polarized dichroism spectroscopy, X-ray diffraction crystallography method,etc. However, these methods are not easy to monitor the denaturation process of BSA aqueous solution in real time. In this study, a homemade optical heterodyne polarimeter that was capable of amplifying the optical rotation signal for 20-fold was built up by authors, and with the use of precision thermoelectric cooler (TEC), a three-part experiments was designed to study the phenomenon of thermal denaturation of BSA aqueous solution after heating. Our results indicated that when BSA aqueous solution is heated to about 67.8°C, the thermal denaturation was observed and the structure of BSA was reversible at this time by cooling down because of protein’s renaturation role. When the temperature was between 70-75°C, its structure was gradually changed from a reversible way to a partially reversible status, and finally the structure became almost irreversible at about more than 75°C. However, although both the concentration of the aqueous protein solution and the rate of heating with TEC system have some effects on the temperature of denaturation, they are not the main factors. When BSA solution was mixed with anionic surfactants – the sodium dodecyl sulfate (SDS), to create different concentration of solution, a certain extent of stable effect on the protein structure was significantly observed when heated by our TEC system. The mixed solution avoided the structure of protein unfolding at denaturation temperature of 67.76 0.34°C, and when its concentration molar ratio [SDS] / [BSA] was about 10, the protective effect reached its maximum, making the denaturation temperature delay about 15°C. These results can not only be applied to the processing of many proteins, but also were consistent with other studies using different methods.