Cellulose crystallinity - a key predictor of the enzymatic hydrolysis rate
Cellulose crystallinity - a key predictor of the enzymatic hydrolysis rate
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DOI：
10.1111/j.1742-4658.2010.07585.x
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发表时间：
2010-03-01
期刊：
影响因子：
5.4
通讯作者：
Bommarius, Andreas S.
中科院分区：
文献类型：
--
作者：
Hall, Melanie;Bansal, Prabuddha;Bommarius, Andreas S.
纤维素的酶促水解遇到了与底物和酶相关的各种限制。虽然纯纤维素Avicel的结晶度在确定纤维素酶从里氏木霉的水解速率中起着重要作用，但我们发现它在酶促转化过程中保持恒定。通过研究纤维素酶对纤维素样品的动力学，研究了纤维素酶的作用方式。因此，开发了一种方便的方法，以达到中等程度的结晶度与Avicel和纤维素酶催化水解纤维素的初始速率被证明是线性成比例的结晶度指数的Avicel。尽管与纤维素酶到纤维素上的吸附能力相关，在给定的酶加载量下，初始酶促速率随着结晶度指数的降低而继续增加，即使结合的酶浓度保持恒定。这一发现支持了结晶度而不是吸附对酶促速率的决定性作用。因此，从各种样品获得的纤维素酶活性和初始速率数据可以提供关于纤维素酶的机械作用和纤维素链的可水解/反应性部分的细节的有价值的信息。X射线衍射提供了对来自T. reesei。在纤维素的转化过程中，纤维素晶体的（021）面被T. reesei。
The enzymatic hydrolysis of cellulose encounters various limitations that are both substrate- and enzyme-related. Although the crystallinity of pure cellulosic Avicel plays a major role in determining the rate of hydrolysis by cellulases from Trichoderma reesei, we show that it stays constant during enzymatic conversion. The mode of action of cellulases was investigated by studying their kinetics on cellulose samples. A convenient method for reaching intermediate degrees of crystallinity with Avicel was therefore developed and the initial rate of the cellulase-catalyzed hydrolysis of cellulose was demonstrated to be linearly proportional to the crystallinity index of Avicel. Despite correlation with the adsorption capacity of cellulases onto cellulose, at a given enzyme loading, the initial enzymatic rate continued to increase with a decreasing crystallinity index, even though the bound enzyme concentration stayed constant. This finding supports the determinant role of crystallinity rather than adsorption on the enzymatic rate. Thus, the cellulase activity and initial rate data obtained from various samples may provide valuable information about the details of the mechanistic action of cellulase and the hydrolysable/reactive fractions of cellulose chains. X-ray diffraction provides insight into the mode of action of Cel7A from T. reesei. In the conversion of cellulose, the (021) face of the cellulose crystal was shown to be preferentially attacked by Cel7A from T. reesei.