肌紅蛋白熱變性之旋光量測研究

Thermal Denaturation Study of Myoglobin using Optical Heterdyne Polarimeter

林志龍(Lin, Chih Lung)

指導教授 ： 吳見明

國立清華大學/原子科學院/生醫工程與環境科學系/碩士(2015年)

摘要

近年來，有許多的量測方法皆可用來研究蛋白質在加熱後其結構之變化，例如差分掃描法、圓偏振二色光譜法、X-ray 晶格繞射法等等，但這些方法皆無法即時量測出蛋白質水溶液在加熱後結構的快速變化。因此本研究使用具有放大旋光訊號效果約41倍的自製光學外差式偏光儀，以及精密的熱電致冷晶片溫度控制器，設計了實驗來詳細探討肌紅蛋白溶液在加熱後的熱變性現象。
實驗結果指出，肌紅蛋白水溶液再加熱至約75°C時，有少部分的蛋白質結構會受到破壞，但此時蛋白質結構是屬於可逆的，在降溫後其結構會因為蛋白質之復性作用而慢慢恢復。而隨著加熱溫度到達75.9±0.1°C，其結構會由可逆逐漸轉變為部分可逆。當溫度加熱到77.5°C再冷卻至25°C時，約80%的結構會恢復。若溫度加熱到80°C再冷卻至25°C時，只剩下52%的結構會恢復。再將溫度加熱到85°C再冷卻至25°C時，會有45%的結構恢復。肌紅蛋白結構主要在75.9°C 到80.4°C 溫度區段受到破壞，當加熱溫度超過80.4°C 時，蛋白質復性作用會隨著溫度升高而減少。

關鍵字

肌紅蛋白 ； 旋光

並列摘要

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.

並列關鍵字

Myoglobin ； Optical Rotation

參考文獻

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