β-环糊精衍生物修饰对去折叠胰蛋白酶酶学性能的影响

Effect of β- cyclodextrin derivative modification on enzyme properties of unfolded trypsin

为了改善天然胰蛋白酶和去折叠胰蛋白酶的酶学性能,采用单-6-脱氧-6-胺基-β-环糊精(CDAN)对它们进行修饰,研究CDAN对它们的相对活性、动力学参数、热稳定性、自溶性及在尿素溶液中稳定性的影响。结果显示:CDAN修饰明显降低了天然和去折叠胰蛋白酶的米氏常数并提高了它们的催化效率,其中去折叠胰蛋白酶的变化最显著(p<0.05),修饰前后去折叠胰蛋白酶的Km值分别为0.35×10-3mol/L和0.11×10-3mol/L。修饰的天然胰蛋白酶在60℃保温10 min时,相对活性由修饰前的2.1%上升至58.3%,而修饰的去折叠胰蛋白酶则从修饰前的19.5%上升至70.5%;在尿素溶液中处理60 min时,修饰前后天然胰蛋白酶的相对活性分别为11.3%和78.8%,而去折叠胰蛋白酶分别为21.3%和84.9%。表明CDAN修饰改善了胰蛋白酶的热稳定性、抗自溶能力以及在尿素溶液中的稳定性,其中去折叠胰蛋白酶的改善效果比天然胰蛋白酶的更好。

Native trypsin and unfolded trypsin are modified by mono-6- deoxy-6- amino-β- cyclodextrin （CDAN） to improve their enzyme properties. The effect of CDAN modification on the relative activity, kinetic parameters, thermal stability, autolysis and stability in the urea of native trypsin and unfolded trypsin was studied. Results showed that there was an obvious decrease in the Km value and increase in the catalytic efficiency （Koot/Km） of native trypsin and unfolded trypsin after modification.And the modified unfolded trypsin showed more obvious（p 〈 0.05） change than modified native trypsin.The Km value of unfolded trypsin was 0.35 × 10-3 mol/L and 0.11 × 10 3 mol/L before and after modification, respectively.After modification the relative activity of native trypsin increased from 2.1% to 58.3% at incubation 10 min at 60 ℃,while that of unfolded trypsin increased from 19.5% to 70.5%. Moreover, before and after modification,the relative activity of native trypsin was 11.3% and 78.8% at incubation 60 min in urea solution, respectively, while that of unfolded trypsin was 21.3% and 84.9%, respectively.The results showed that unfolded trypsin showed more obvious improvement in the thermal stability, autolysis and stability in the urea after modification in comparison to native trypsin.