Abstract Phenolic compounds released during pretreatment of lignocellulosic biomass influence its enzymatic hydrolysis. To understand the effects of these compounds on the kinetic properties of xylan-degrading enzymes, the present study employed the recombinant cellulosomal endo-β-1,4-xylanase, thermostable GH11 XynA protein from Clostridium thermocellum, as an enzyme model to evaluate the effects of 4-hydroxybenzoic acid, gallic acid, vanillin, tannic acid, p-coumaric acid, ferulic acid, syringaldehyde, and cinnamic acid. XynA was deactivated by the assayed phenols at 60 °C, presenting the strongest deactivation in the presence of tannic acid, with an activity reduction of about 80 %. Thermal stability of XynA was influenced by ferulic acid, syringaldehyde, cinnamic acid, 4-hydroxybenzoic acid, and p-coumaric acid. The hydrolysis rate of oat-spelt xylan by XynA was influenced by temperature, being unable to hydrolyze at 40 °C in the presence of tannic acid. On hydrolysis at 60 °C, the presence of gallic and tannic acid caused a major reduction in reducing sugar production, generating 3.74 and 2.15 g.L-1 of reducing sugar, respectively, whereas the reaction in the absence of phenols generated 4.41 g.L-1. When XynA was pre-deactivated by phenols it could recover most of its activity at 40 °C, however, at 60 °C activity could not be reestablished.

中文翻译：

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木质素衍生酚类化合物对热纤梭菌内切-β-1,4-木聚糖酶 XynA 的影响

摘要 木质纤维素生物质预处理过程中释放的酚类化合物会影响其酶水解。为了了解这些化合物对木聚糖降解酶动力学特性的影响，本研究采用来自热纤梭菌的重组纤维素内切-β-1,4-木聚糖酶、热稳定的 GH11 XynA 蛋白作为酶模型来评估影响4-羟基苯甲酸、没食子酸、香草醛、鞣酸、对香豆酸、阿魏酸、丁香醛和肉桂酸。XynA 在 60 °C 下被测定的酚类失活，在单宁酸存在下表现出最强的失活，活性降低约 80%。XynA 的热稳定性受阿魏酸、丁香醛、肉桂酸、4-羟基苯甲酸和对香豆酸的影响。XynA对燕麦-拼写木聚糖的水解速率受温度影响，在单宁酸存在下40°C不能水解。在 60 °C 下水解时，没食子酸和单宁酸的存在导致还原糖产量大幅减少，分别产生 3.74 和 2.15 gL-1 的还原糖，而在没有苯酚的情况下反应产生 4.41 gL-1。当 XynA 被酚类预失活时，它可以在 40 °C 下恢复其大部分活性，但是，在 60 °C 下无法重新建立活性。而在没有苯酚的情况下反应生成 4.41 gL-1。当 XynA 被酚类预失活时，它可以在 40 °C 下恢复其大部分活性，但是，在 60 °C 下无法重新建立活性。而在没有苯酚的情况下反应生成 4.41 gL-1。当 XynA 被酚类预失活时，它可以在 40 °C 下恢复其大部分活性，但是，在 60 °C 下无法重新建立活性。