The Role of Evolving Interfacial Substrate Properties on Heterogeneous Cellulose Hydrolysis Kinetics,ACS Sustainable Chemistry & Engineering

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The Role of Evolving Interfacial Substrate Properties on Heterogeneous Cellulose Hydrolysis Kinetics
ACS Sustainable Chemistry & Engineering ( IF 7.1 ) Pub Date : 2020-04-07 , DOI: 10.1021/acssuschemeng.0c00779
Jennifer Danger Nill _{1,

2} , Tina Jeoh ₃

Affiliation

Interfacial enzyme reactions require formation of an enzyme–substrate complex at the surface of a heterogeneous substrate, but often multiple modes of enzyme binding and types of binding sites complicate analysis of their kinetics. Excess heterogeneous substrate is often used as a justification to model the substrate as unchanging, but using the study of the enzymatic hydrolysis of insoluble cellulose as an example, we argue that reaction rates are dependent on evolving substrate interfacial properties. We hypothesize that the relative abundance of binding sites on cellulose where hydrolysis can occur (productive binding sites) and binding sites where hydrolysis cannot be initiated or is inhibited (nonproductive binding sites) contribute to rate limitations. We show that the initial total number of productive binding sites (the productive binding capacity) determines the magnitude of the initial burst phase of cellulose hydrolysis, while productive binding site depletion explains overall hydrolysis kinetics. Furthermore, we show that irreversibly bound surface enzymes contribute to the depletion of productive binding sites. Our model shows that increasing the ratio of productive to nonproductive binding sites promotes hydrolysis, while maintaining an elevated productive binding capacity throughout conversion is key to preventing hydrolysis slowdown.

中文翻译：

界面基质性质的演变对纤维素非均相水解动力学的影响

界面酶反应需要在异质底物表面形成酶-底物复合物，但是酶结合的多种模式和结合位点的类型通常会使动力学分析变得复杂。过量的异质底物通常被用作将底物模型模拟为不变的理由，但是以不溶性纤维素的酶水解研究为例，我们认为反应速率取决于不断发展的底物界面性质。我们假设纤维素上可能发生水解的结合位点（生产性结合位点）和无法开始或被抑制水解的结合位点（非生产性结合位点）的相对丰度会限制速率。我们表明，生产性结合位点的初始总数（生产性结合能力）决定了纤维素水解初始爆发阶段的幅度，而生产性结合位点的耗竭则说明了整体水解动力学。此外，我们表明不可逆结合的表面酶有助于生产结合位点的消耗。我们的模型表明，提高生产性结合位点与非生产性结合位点的比例可促进水解，而在整个转化过程中保持提高的生产性结合能力是防止水解减慢的关键。我们表明不可逆结合的表面酶有助于生产性结合位点的消耗。我们的模型表明，提高生产性结合位点与非生产性结合位点的比例可促进水解，而在整个转化过程中保持提高的生产性结合能力是防止水解减慢的关键。我们表明不可逆结合的表面酶有助于生产结合位点的消耗。我们的模型表明，提高生产性结合位点与非生产性结合位点的比例可促进水解，而在整个转化过程中保持提高的生产性结合能力是防止水解减慢的关键。

更新日期：2020-04-07

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