采用TG和DSC方法研究糖类对谷氨酰胺转胺酶热稳定性的影响

谷氨酰胺转胺酶(TGase)是一种催化蛋白质分子间产生共价交联的硫醇酶类,但其热稳定性较差。在40～60℃之间,通过添加海藻糖、蔗糖和葡萄糖作为TGase的保护剂,TGase酶活残留率均比对照组升高,其中海藻糖的保护最为显著。采用TG和DSC分析方法,与对照组相比,三种糖中海藻糖提高了TGase的相变温度(Tm),△Tm值为29℃,相变热焓△H上升26.4J/g,失重率降低了2.8%。对应于上述热力学参数,葡萄糖和蔗糖的加入则并未表现与海藻糖相同的趋势。

Effects Study on Thermal Stabilization of Transglutaminase in Presence of Saccharides by TG/DSC Method

Transglutaminase (TGase, EC 2.3.2.13) was one of the thiol enzymes that can catalyze protein reticulation, but its enzyme activity was unstable in normal temperature. Thermal stability tests were tested from 40℃ to 60℃, and the results showed that the remained enzyme activity of TGase were increased in protection of glucose, sucrose and trehalose, and the trehalose was highest in all the tests. The samples were studied by TG (therm-gravimtry) and DSC (differential scanning calorimetry) analysis whereas, the results showed that the increas of △Tm and △H of TGase in trehalose were 29℃ and 26.4J/g, respectively. The rate of loss weight of TGase in trehalose reduced 2.8%. However, these thermodynamics parameters (△Tm, △H and loss weight) did not show the same trend as in trehalose when sucrose and glucose were added.