Inhibition kinetics of acetosyringone on xylanase in hydrolysis of hemicellulose

Many phenolic compounds, derived from lignin during the pretreatment of lignocellulosic biomass, could obviously inhibit the activity of cellulolytic and hemicellulolytic enzymes. Acetosyringone (AS) is one of the phenolic compounds produced from lignin degradation. In this study, we investigated the inhibitory effects of AS on xylanase activity through kinetic experiments. The results showed that AS could obviously inhibit the activity of xylanase in a reversible and noncompetitive binding manner (up to 50% activity loss). Inhibitory kinetics and constants of xylanase on AS were conducted by the HCH-1 model (<i>β</i> = 0.0090 ± 0.0009 mM⁻¹). Furthermore, intrinsic and 8-anilino-1-naphthalenesulfonic (ANS)-binding fluorescence results showed that the tertiary structure of AS-mediated xylanase was altered. These findings provide new insights into the role of AS in xylanase activity. Our results also suggest that AS was an inhibitor of xylanase and targeting AS was a potential strategy to increase xylose production. Acetosyringone inhibited xylanase activity in a reversible and non-competitive binding manner, which might be related to the disruption of tertiary structure of xylanase.

木质纤维素生物质预处理过程中从木质素衍生出的多种酚类化合物，可显著抑制纤维素酶与半纤维素酶的活性。乙酰丁香酮（Acetosyringone，AS）是木质素降解产生的酚类化合物之一。本研究通过动力学实验，探究了AS对木聚糖酶活性的抑制作用。结果表明，AS可通过可逆非竞争性结合方式显著抑制木聚糖酶活性，最高可使酶活损失达50%。本研究采用HCH-1模型分析了AS对木聚糖酶的抑制动力学参数与抑制常数（β=0.0090±0.0009 mM⁻¹）。此外，内源荧光与8-苯胺基-1-萘磺酸（8-anilino-1-naphthalenesulfonic，ANS）结合荧光实验结果显示，经AS作用后的木聚糖酶三级结构发生了改变。上述研究结果为解析AS对木聚糖酶活性的调控机制提供了新视角。本研究结果同时表明，AS是木聚糖酶的抑制剂，靶向调控AS或是提升木糖产量的潜在策略。乙酰丁香酮通过可逆非竞争性结合方式抑制木聚糖酶活性，这一作用可能与木聚糖酶三级结构的破坏有关。