Chen Nan, Fan Jun-Bao, Xiang Jin, Chen Jie, Liang Yi
State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China.
Biochim Biophys Acta. 2006 Jun;1764(6):1029-35. doi: 10.1016/j.bbapap.2006.03.015. Epub 2006 Apr 4.
The activities of cellulases from Trichoderma reesei entrapped in three types of reverse micelles have been investigated using microcrystalline cellulose as the substrate. The reverse micellar systems are formed by nonionic surfactant Triton X-100, anionic surfactant Aerosol OT (AOT), and cationic surfactant cetyltrimethyl ammonium bromide (CTAB) in organic solvent media, respectively. The influences of the molar ratio of water to surfactant omega0, one of characteristic parameters of reverse micelles, and other environmental conditions including pH and temperature, on the enzymatic activity have been studied in these reverse micellar systems. The results obtained indicate that these three reverse micelles are more effective than aqueous systems for microcrystalline cellulose hydrolysis, and cellulases show "superactivity" in these reverse micelles compared with that in aqueous systems under the same pH and temperature conditions. The enzymatic activity decreases with the increase of omega0 in both AOT and Triton X-100 reverse micellar systems, but reaches a maximum at omega0 of 16.7 for CTAB reverse micelles. Temperature and pH also influence the cellulose hydrolysis process. The structural changes of cellulases in AOT reverse micelles have been measured by intrinsic fluorescence method and a possible explanation for the activity changes of cellulases has been proposed.
以微晶纤维素为底物，研究了包裹在三种反胶束中的里氏木霉纤维素酶的活性。反胶束体系分别由非离子表面活性剂吐温X-100、阴离子表面活性剂气溶胶OT（AOT）和阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）在有机溶剂介质中形成。研究了反胶束特征参数之一的水与表面活性剂的摩尔比ω0以及其他环境条件（包括pH值和温度）对这些反胶束体系中酶活性的影响。所得结果表明，这三种反胶束在微晶纤维素水解方面比水相体系更有效，并且在相同pH值和温度条件下，与水相体系相比，纤维素酶在这些反胶束中表现出“超活性”。在AOT和吐温X-100反胶束体系中，酶活性均随ω0的增加而降低，但在CTAB反胶束中，ω0为16.7时酶活性达到最大值。温度和pH值也影响纤维素水解过程。采用内源荧光法测定了纤维素酶在AOT反胶束中的结构变化，并对纤维素酶活性变化提出了一种可能的解释。
