【摘要】 本文用P/EDSC-2型差示扫描量热计检测了11个具低水含量的高纯蛋白质的DSC曲线.发现它们无一例外地在变性峰前都具有小的吸热峰,即热变性前峰.实验表明变性峰和前峰的峰温、峰面积都强烈现依赖于蛋白质的含水量,而且样品被第一次扫描后在室温放置一定时间后前峰仍可以再现,再现前峰的峰温和峰面积取决于样品的水合度、第一次被扫描的终止温度以及第一次扫描后在室温放置的时间.本文还检测了一些多聚物、氨基酸、多肽以及热变性后蛋白质的DSC曲线.发现热变性后的蛋白质仍可出现前峰,但变性峰不再出现,显然两个峰的出现机制不同.本文并就前峰出现的可性能机制进行了初步讨论.更多还原

【Abstract】 This paper reports the observations of the DSC heating scanning curves of seven different kinds of hydrated proteins with high purity from eleven sources. The observation has shown that there is an obvious low temperature endothermal peak for all of the orotein samples used. It was named as a <<PreThermodenature Peak>> (PD peak).The heating scanning curves of lysozyme with various water contents were measured. Both denaturation peak and PD peak are strongly dependent on the water content. The peak-temperature of PD peak,Tpd, decreases with the.increase in degree of hydration and there is a break at about R = 0.1 g water/g protein. Tpd drops down to 315 K when R = 0.45. The enthalpy change of PD peak, Hpd, increases firstly with the increase in hydration degree and reaches the maximum 8.0 Kcal/mole at R=0.19. Then Hpd decreases with further increase in water content. The PD peak disappears at R = 0.45.The reappearance phenomenon of the PD peak was observed when the scanned samples are kept at room temperature for a certain period of time. The reappearance dynamics was followed. Both Tpd and Hpd of reappenred peak depend on the hydration degree of sample, the length of the time of keeping the scanned sample at room temperature and the temperature at which first scan was ended.The PD peak was checked on some polymers, amino acids, polypeptids and denatured proteins. It is interesting to be found that the protein after thermal denaturation displays again a PD peak but no denaturation peak. Apparently, the PD peak and denaturation peak have different origin.The possible mechanism of PD peak is discussed.更多还原