内切纤维素酶在纤维素底物上的初始吸附动力学  

Studies On the Initial Adsorption Kinetics of Endocellulases on Cellulose Substrate

作　　者：秦薇薇[1] 付时雨[1] 刘浩[1] 柴欣生[1] 詹怀宇[1] 

机构地区：[1]华南理工大学制浆造纸工程国家重点实验室,广东广州510640

出　　处：《造纸科学与技术》2011年第3期66-70,59,共6页Paper Science & Technology

基　　金：国家973项目(2010BC732206);国家自然科学基金(30972324)

摘　　要：应用双波长紫外分光光度法实时监测了两种内切纤维素酶(EGV和EGI)在α-纤维素上的初始吸附,并结合动力学方程探讨了可能的吸附机理。实验结果表明,带纤维素结合域(CBD)的内切纤维素酶在底物上的吸附非常迅速,仅需4min左右即可达到准稳态,其吸附动力学曲线与准二阶动力学模型的预测值几乎完全一致。通过改变纤维素酶EGV的初始浓度得到的平衡吸附数据符合Langmuir等温吸附模型,表明该酶的初始吸附可能是单分子层化学吸附。内切纤维素酶EGI的吸附动力学较为复杂,约每7min即发生明显的脱附,然后重新吸附。内切纤维素酶的特异性吸附是由CBD决定的,缺少CBD的内切纤维素酶以缔合的形式沉积在纤维表面,其吸附动力学更多依赖于其胶体化学性质。The initial adsorption of two endoglucanases（EGV and EGI） on α-cellulose was monitored by using the dual-wavelength ultraviolet spectroscopic method.The possible adsorption mechanism was also discussed according to the adsorption kinetic models.The results show that the adsorption of the endoglucanase with cellulose binding domains（CBD）,EGV,on the cellulose substrate is very fast.A pseudo steady state can be observed in only about 4 min.The adsorption curve of EGV almost exactly fits that predicted by the pseudo-second-order kinetic equation.The equilibrium data measured by altering the initial cellulase concentration agrees very well with the Langmuir isotherm model.The initial adsorption of EGV on cellulose substrate is thus probably monolayer adsorption.The adsorption of EGI is more complex.A significant desorption occurs about every 7 min,and then a re-adsorption starts.It was assumed that the specific adsorption of endoglucanase on cellulose substrate depends on the action of CBD.For EGI without CBD,the enzyme particles tend to associate with each other and deposit on the substrate surface of fibers in the form of aggregates.Therefore,the adsorption kinetics for EGI strongly depends on its colloidal properties.

关 键 词：内切纤维素酶 初始吸附 纤维素结合域 动力学模型 等温吸附 

分 类 号：Q55[生物学—生物化学]