Laccases have been widely explored for their ligninolytic capability in bioethanol production and bioremediation of industrial effluents. However, low reaction rates have posed a major challenge to commercialization of such processes. This study reports the first evidence of laccase inhibition by two types of lignin degradation intermediates – fungal-solubilized lignin and alkali-treated lignin – thus offering a highly plausible explanation for low reaction rates due to buildup of inhibitors during the actual process. Reversed-phase high-performance liquid chromatography revealed the presence of similar polar compounds in both lignin samples. A detailed kinetic study on laccase, using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) as the substrate, was used to calculate the Michaelis constant (K_m) and maximum reaction rate (V_max). With an increase in the concentration of lignin degradation intermediates, V_max remained nearly constant, while K_m increased from 1.3 to 4.0 times that of pure laccase, revealing that the inhibition was competitive in nature. The kinetic studies reported here and the insight gained into the nature of inhibition can help design process strategies to mitigate this effect and improve overall process efficiency. This work is applicable to processes that employ laccase for delignification of biomass, such as second-generation biofuels processes, as well as for industrial effluent treatment in paper and pulp industries.

漆酶在生物乙醇生产和工业废水的生物修复中具有木质素分解能力，因此已被广泛研究。但是，低反应速率对此类方法的商业化提出了重大挑战。这项研究报告了两种类型的木质素降解中间体（真菌可溶的木质素和碱处理的木质素）对漆酶的抑制作用的第一个证据，从而为在实际过程中由于抑制剂的积累而导致的低反应速率提供了一个非常合理的解释。反相高效液相色谱显示两个木质素样品中均存在相似的极性化合物。以2,2'-叠氮基双（3-乙基苯并噻唑啉-6-磺酸）（ABTS）为底物对漆酶进行详细的动力学研究，以计算米氏常数（K _m）和最大反应速率（V _max）。随着木质素降解中间体浓度的增加，V _max几乎保持恒定，而K _m从纯漆酶的1.3倍增加到4.0倍，这表明抑制作用具有竞争性。此处报道的动力学研究以及对抑制性质的深入了解有助于设计工艺策略来减轻这种影响并提高总体工艺效率。这项工作适用于使用漆酶对生物质进行脱木质素的工艺，例如第二代生物燃料工艺，以及造纸和纸浆工业中的工业废水处理。