Tébéka Iris R M, Silva Artur G L, Petri Denise F S
Instituto de Quimica, Universidade de Sao Paulo, Av. Prof. Lineu Prestes 748, 05508-900 Sao Paulo, Brazil.
Langmuir. 2009 Feb 3;25(3):1582-7. doi: 10.1021/la802882s.
Cellulase is an enzymatic complex which synergically promotes the degradation of cellulose to glucose. The adsorption behavior of cellulase from Trichoderma reesei onto Si wafers or amino-terminated surfaces was investigated by means of ellipsometry and atomic force microscopy (AFM) as a function of temperature. Upon increasing temperature from (24 +/- 1) to (60 +/- 1) degrees C, adsorption of cellulase became faster and more pronounced and the mean roughness of cellulase adsorbed layers increased. In the case of cellulase adsorbed onto Si wafers, Arrhenius's plot allowed us to estimate the adsorption energy as 24.2 kJ mol(-1). The hydrolytic activity of free cellulase and cellulase immobilized onto Si wafers was tested using cellulose dispersions as substrates. The incubation temperature ranged from (37 +/- 1) to (60 +/- 1) degrees C. The highest efficiency was observed at (60 +/- 1) degrees C. The amount of glucose produced by free cellulase was approximately 20% higher than that obtained from immobilized cellulase. However, immobilizing cellulase onto Si wafers proved to be advantageous because they could be reused six times while retaining their original activity level. Such an effect was attributed to surface hydration, which prevents enzyme denaturation. The hydrolytic activity of cellulase immobilized onto amino-terminated surfaces was slightly lower than that observed for cellulase adsorbed onto Si wafers, and reuse was not possible.
纤维素酶是一种协同促进纤维素降解为葡萄糖的酶复合物。通过椭圆偏振光法和原子力显微镜（AFM）研究了里氏木霉纤维素酶在硅片或氨基端表面上的吸附行为随温度的变化。温度从（24±1）℃升高到（60±1）℃时，纤维素酶的吸附变得更快且更明显，纤维素酶吸附层的平均粗糙度增加。在纤维素酶吸附到硅片的情况下，根据阿累尼乌斯图，我们估计吸附能为24.2 kJ mol⁻¹。以纤维素分散体为底物，测试了游离纤维素酶和固定在硅片上的纤维素酶的水解活性。孵育温度范围为（37±1）℃至（60±1）℃。在（60±1）℃时观察到最高效率。游离纤维素酶产生的葡萄糖量比固定化纤维素酶获得的葡萄糖量高出约20%。然而，将纤维素酶固定在硅片上被证明是有利的，因为它们可以重复使用六次，同时保持其原始活性水平。这种效果归因于表面水合作用，它可防止酶变性。固定在氨基端表面上的纤维素酶的水解活性略低于吸附在硅片上的纤维素酶，并且无法重复使用。
