Väljamäe Priit, Kipper Kalle, Pettersson Göran, Johansson Gunnar
Institute of Molecular and Cell Biology, University of Tartu, Vanemuise 46-138, Tartu 51010, Estonia.
Biotechnol Bioeng. 2003 Oct 20;84(2):254-7. doi: 10.1002/bit.10775.
A fractal-like kinetics model was used to describe the synergistic hydrolysis of bacterial cellulose by Trichoderma reesei cellulases. The synergistic action of intact cellobiohydrolase Cel7A and endoglucanase Cel5A at low enzyme-to-substrate ratios showed an apparent substrate inhibition consistent with a case where two-dimensional (2-D) surface diffusion of the cellobiohydrolase is rate-limiting. The action of Cel7A core and Cel5A was instead consistent with a three-dimensional (3-D) diffusion-based mode of action. The synergistic action of intact Cel7A was far superior to that of the core at a high enzyme-to-substrate ratio, but this effect was gradually reduced at lower enzyme-to-substrate ratios. The apparent fractal kinetics exponent h obtained by nonlinear fit of hydrolysis data to the fractal-like kinetics analogue of a first-order reaction was a useful empirical parameter for assessing the rate retardation and its dependence on the reaction conditions.
采用类分形动力学模型描述里氏木霉纤维素酶对细菌纤维素的协同水解作用。在低酶底物比下，完整的纤维二糖水解酶Cel7A和内切葡聚糖酶Cel5A的协同作用表现出明显的底物抑制，这与纤维二糖水解酶二维（2-D）表面扩散限速的情况一致。相反，Cel7A核心和Cel5A的作用与基于三维（3-D）扩散的作用模式一致。在高酶底物比下，完整Cel7A的协同作用远优于其核心部分，但在较低酶底物比下，这种效果逐渐减弱。通过将水解数据与一级反应的类分形动力学类似物进行非线性拟合得到的表观分形动力学指数h是评估速率阻滞及其对反应条件依赖性的一个有用的经验参数。
