Tanaka M, Ikesaka M, Matsuno R, Converse A O
Department of Food Science and Technology, Faculty of Agriculture, Kyoto University, Kitashirakawa, Kyoto 606, Japan.
Biotechnol Bioeng. 1988 Aug 20;32(5):698-706. doi: 10.1002/bit.260320515.
The effect of cellulase size on hydrolysis was studied by comparing the behavior of crosslinked cellulase (CC) with normal cellulase (FC). The average molecular weight of the CC was at least three times the molecular weight of the FC. The amounts of each enzyme were adjusted so that the degree of solubilization after 2 h was the same. The degree of solubilization of Avicel with CC was higher than that with FC in the late stage of reaction. The degree of solubilization of pretreated lignocelluloses was much greater than that of Avicel, but the degree of solubilization with CC was lower than that with FC at all times during the reaction. The degree of solubilization of artificial lignified Avicel was higher with FC than with CC, but the degree of solubilization of de-lignified the artificial lignified Avicel was lower with FC than with CC. The degree of solubilization of amorphous cellulose with FC was the same as that with CC at all times during the reaction. These behaviors are examined by the hypothesis that when small pores dominate, the smaller enzyme components diffuse into the pores and become inactive since synergism with the larger components is no longer possible, whereas, when larger pores dominate, the entire enzyme can diffuse in and therefore the available surface area is increased. This hypothesis is supported by direct measurement of the pore size in two of the substrates and by diffusion inside Avicel of only smaller molecular cellulase component.
通过比较交联纤维素酶（CC）和普通纤维素酶（FC）的行为，研究了纤维素酶大小对水解的影响。CC的平均分子量至少是FC分子量的三倍。调整每种酶的用量，使2小时后的溶解程度相同。在反应后期，用CC处理的微晶纤维素的溶解程度高于用FC处理的。预处理木质纤维素的溶解程度远大于微晶纤维素，但在反应的所有阶段，用CC处理的溶解程度均低于用FC处理的。人工木质化微晶纤维素用FC处理的溶解程度高于用CC处理的，但脱木质化的人工木质化微晶纤维素用FC处理的溶解程度低于用CC处理的。在反应的所有阶段，用FC处理的无定形纤维素的溶解程度与用CC处理的相同。这些行为通过以下假设进行检验：当小孔占主导时，较小的酶组分扩散到孔中并变得无活性，因为与较大组分的协同作用不再可能，而当大孔占主导时，整个酶可以扩散进去，因此可用表面积增加。这一假设得到了对两种底物孔径的直接测量以及仅较小分子纤维素酶组分在微晶纤维素内部扩散的支持。
