Camarero Susana, Cañas Ana I, Nousiainen Paula, Record Eric, Lomascolo Anne, Martínez Maria Jesús, Martínez Angel T
Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, E-28040 Madrid, Spain.
Environ Sci Technol. 2008 Sep 1;42(17):6703-9. doi: 10.1021/es8008979.
The capabilities of p-coumaric acid (PCA), ferulic acid (FA), and sinapic acid (SA) as laccase mediators are compared in oxidation of industrial dyes and polycyclic aromatic hydrocarbons (PAH). SA behaved as highly efficient mediator in decolorization of dyes, including the recalcitrant Reactive Black 5. This mediating capacity was related to the specificity constant of the enzyme oxidizing this p-hydroxycinnamic acid, which was 16 times higher than for the typical substrate 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS). The kinetics of ABTS oxidation by laccase in the presence of p-hydroxycinnamic acids suggested that the stable phenoxyl radical of a SA transformation product acts as laccase mediator. On the other hand, FA and, especially PCA, easily mediated benzo[a]pyrene oxidation, the latter also promoting the oxidation of the more recalcitrant phenanthrene. Phenanthrene transformation by laccase-PCA was enhanced by Tween 80. This fact, together with the detection of TBARS (thiobarbituric acid-reactive-substances) from unsaturated fatty acids, revealed that laccase can also initiate lipid peroxidation reactions in the presence of p-hydroxycinnamic acids enabling oxidation of the most recalcitrant PAH.
对香豆酸（PCA）、阿魏酸（FA）和芥子酸（SA）作为漆酶介体在工业染料和多环芳烃（PAH）氧化中的能力进行了比较。SA在包括顽固性活性黑5在内的染料脱色中表现为高效介体。这种介导能力与氧化该对羟基肉桂酸的酶的特异性常数有关，该常数比典型底物2,2'-偶氮双（3-乙基苯并噻唑啉-6-磺酸）（ABTS）高16倍。在对羟基肉桂酸存在下漆酶氧化ABTS的动力学表明，SA转化产物的稳定苯氧基自由基充当漆酶介体。另一方面，FA，尤其是PCA，容易介导苯并[a]芘氧化，后者还促进了更难降解的菲的氧化。吐温80增强了漆酶-PCA对菲的转化。这一事实，连同从不饱和脂肪酸中检测到硫代巴比妥酸反应性物质（TBARS），表明漆酶在对羟基肉桂酸存在下也能引发脂质过氧化反应，从而实现最难降解的PAH的氧化。
