Chemical Engineering, Queen's University, Kingston, ON K7L 3N6, Canada.
Appl Microbiol Biotechnol. 2013 Jul;97(14):6263-9. doi: 10.1007/s00253-012-4525-y. Epub 2012 Nov 6.
Laccases produced by white rot fungi have been extensively evaluated for their potential to decolorize textile wastewaters which contain salts like sodium chloride and sodium sulfate. The effect of sodium chloride and sodium sulfate on Trametes versicolor laccase during the decolorization of an anthraquinone dye (Reactive Blue 19) and the oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) were evaluated by steady-state kinetic analysis. The results showed that, while sodium sulfate did not affect laccase activity, sodium chloride inhibited both ABTS oxidation and dye decolorization. However, the type of inhibition was substrate-dependent: it was hyperbolic, noncompetitive with ABTS and parabolic, noncompetitive with Reactive Blue 19. Furthermore, the results suggested that two chlorides may bind to laccase in the presence of the dye unlike recent inhibition models which suggest that there is only one inhibition site. This investigation is the first to provide evidence for and to propose a two-site model of laccase inhibition, providing new insight into NaCl inhibition of laccase. The proposed model is also useful to predict decolorization rates in the presence of sodium chloride and to determine operating conditions that will minimize inhibition.
白腐真菌产生的漆酶已被广泛评估用于对含有盐（如氯化钠和硫酸钠）的纺织废水进行脱色。通过稳态动力学分析评估了氯化钠和硫酸钠对杂色云芝漆酶在蒽醌染料（活性蓝 19）脱色和 2,2'-联氮双（3-乙基苯并噻唑啉-6-磺酸）（ABTS）氧化过程中的影响。结果表明，虽然硫酸钠不影响漆酶活性，但氯化钠抑制 ABTS 氧化和染料脱色。然而，抑制类型取决于底物：对 ABTS 呈双曲线、非竞争性，对活性蓝 19 呈抛物线、非竞争性。此外，结果表明，两种氯离子可能在染料存在的情况下结合到漆酶上，这与最近的抑制模型不同，后者表明只有一个抑制位点。这项研究首次提供了漆酶抑制的双位点模型的证据，并提出了一个双位点模型，为 NaCl 对漆酶的抑制提供了新的见解。所提出的模型也可用于预测在存在氯化钠的情况下的脱色速率，并确定将抑制作用最小化的操作条件。
