Lignocellulosic biomass conversion using cellulases/polygalacturonases is a process that can be progressively influenced by several determinants involved in cellulose microfibril degradation. The current paper focuses on the kinetics and thermodynamics of thermal inactivation of recombinant E. coli cellulases, cel12B, cel8C, and a polygalacturonase, peh 28, derived from Pectobacterium carotovorum sub sp. carotovorum. Several consensus motifs conferring the enzymes’ thermal stability in both cel12B and peh28 model structures have been detailed earlier, which were confirmed for the three enzymes through the current study of their thermal inactivation profiles over the 20-80 °C range using the respective activities on carboxymethylcellulose and polygalacturonic acid. Kinetic constants and half-lives of thermal inactivation, inactivation energy, plus inactivation entropies, enthalpies and Gibbs free energies, revealed high stability, less conformational change and protein unfolding for cel12B and peh28 due to thermal denaturation compared to cel8C. The apparent thermal stability of peh28 and cel12B, along with their hydrolytic efficiency on a lignocellulosic biomass conversion as reported previously, makes these enzymes candidates for various industrial applications. Analysis of the Gibbs free energy values suggests that the thermal stabilities of cel12B and peh28 are entropy-controlled over the tested temperature range.

中文翻译：

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重组大肠杆菌纤维素酶cel12B，cel8C和聚半乳糖醛酸酶peh28的热灭活动力学和热力学；用于生产生物燃料前体的生物催化剂。

使用纤维素酶/聚半乳糖醛酸酶的木质纤维素生物质转化是一个过程，该过程可以逐渐受到纤维素微原纤维降解中涉及的几种决定因素的影响。目前的论文集中在重组大肠杆菌纤维素酶cel12B，cel8C和多聚半乳糖醛酸酶peh 28的热失活的动力学和热力学上，该酶来自于Carotovorum sub sp.。胡萝卜素。几个共识主题先前已详细介绍了在cel12B和peh28模型结构中赋予酶热稳定性的方法，并通过对羧甲基纤维素和聚半乳糖醛酸的各自活性进行了当前研究，证实了这三种酶在20-80°C范围内的热失活特性。酸。与cel8C相比，由于热变性，cel12B和peh28的热失活，失活能量，失活熵，焓和吉布斯自由能的动力学常数和半衰期显示出较高的稳定性，构象变化和蛋白质解折叠较少。如前所述，peh28和cel12B的表观热稳定性以及它们对木质纤维素生物质转化的水解效率使这些酶成为各种工业应用的候选。