The inhibitory effect of eight model lignin derivatives (ferulic acid, guaiacol, kraft lignin (alkali, low sulfonate content), p-coumaric acid, gallic acid, syringic acid, vanillin and vanillic acid) on XynA activity was evaluated. The model lignin derivatives viz. gallic acid, vanillic acid and vanillin were inhibitory to XynA activity, with an over 50% reduction in activity at concentrations as low as 0.5 mg/ml. However, enzyme deactivation studies in the absence of substrate showed that these pretreatment by-products do not interact with the enzyme except when in the presence of its substrate. The effect of the main structural properties of the pretreatment-derived phenolics, for example their hydroxyl and carbonyl group types, on XynA enzyme inhibition was investigated. The presence of carbonyl groups in phenolics appeared to confer stronger inhibitory effects than hydroxyl groups on XynA activity. The hydrolytic potential of XynA was not inhibited by a mixture of phenolics derived after steam pretreatment of woody biomass (Douglas fir and Black wattle). It appears as if the liquors from steam-pretreated woody biomass did not possess high enough phenolic content to confer XynA inhibition. The xylanase (XynA from Thermomyces lanuginosus) is, therefore, a striking choice for application in biofuel and fine chemical industries for the xylan degradation in steam-pretreated biomass.

八种模型木质素衍生物（阿魏酸、愈创木酚、硫酸盐木质素（碱、低磺酸盐含量）、p-香豆酸、没食子酸、丁香酸、香草醛和香草酸）对 XynA 活性的影响。模型木质素衍生物即。没食子酸、香草酸和香草醛对 XynA 活性有抑制作用，在低至 0.5 mg/ml 的浓度下活性降低 50% 以上。然而，在没有底物的情况下酶失活研究表明，这些预处理副产物不与酶相互作用，除非存在底物。研究了预处理衍生的酚类物质的主要结构特性，例如它们的羟基和羰基类型，对 XynA 酶抑制的影响。酚醛树脂中羰基的存在似乎比羟基对 XynA 活性具有更强的抑制作用。XynA 的水解潜力不受木质生物质（花旗松和黑荆）蒸汽预处理后衍生的酚类混合物的抑制。看起来好像来自蒸汽预处理的木质生物质的液体不具有足够高的酚含量以赋予 XynA 抑制作用。木聚糖酶（XynA 来自因此，Thermomyces lanuginosus ) 是生物燃料和精细化工行业应用蒸汽预处理生物质中木聚糖降解的绝佳选择。