Abstract
Recently, many measurement methods have been used to study structural changes of proteins after heating, such as differential scanning calorimetry method, circularly polarized dichroism spectroscopy, X-ray diffraction crystallography method, etc. However, it is difficult for these methods to monitor the denaturation process of myoglobin solution in real time. In this study, a self-assembled optical heterodyne polarimeter capable of amplifying the optical rotation signal to 41-fold, and a precision thermoelectric cooler (TEC) were used to study the thermal denaturation phenomenon of myoglobin solution after heating. Our results indicate that the protein structure of myoglobin solution has about 5% destroyed by heating to 75℃, however, by cooling down, the protein structure is reversible at this time because of protein renaturation role. When myoglobin solution was heated to about 75.9±0.1°C,its protein structure was gradually changed from reversible to partially reversible. As the myoglobin solution was heated to 77.5℃ and then cooled down to room temperature, about 80% of proteins reversed to original protein structure. Furthermore, as the myoglobin was heated to 80℃ and 85℃, there was 52% and 45%, respectively, proteins to be reversible to the original form. The helical structure of myoglobin were mostly destroyed between 75.9 and 80.4℃. Upon cooling to 25℃ from tempertures above 80.4℃,the recovered helical structure decreased with rise of temperature before cooling.