The multi-copper Laccase enzyme corresponds to one of the most investigated oxidoreductases for potential uses in xenobiotic bioremediation. In this work, we have investigated the photo-degradation process of Laccase from Trametesversicolor induced by UVB light and the influence on its activity over selected substrates. Laccase undergoes photo-degradation when irradiated with UVB light, and the process depends on the presence of oxygen in the medium. With the kinetic data obtained from stationary and time resolved measurements, a photo-degradation mechanism of auto-sensitization was proposed for the enzyme. Laccase generates singlet oxygen, by UVB light absorption, and this reactive oxygen species can trigger the photo-oxidation of susceptible amino acids residues present in the protein structure. The catalytic activity of Laccase was evaluated before and after UVB photolysis over hydroxy-aromatic compounds and substituted phenols which represent potential pollutants. The dye bromothymol blue, the antibiotic rifampicin and the model compound syringaldazine, were selected as substrates. The values of the kinetic parameters determined in our experiments indicate that the photo-oxidative process of Laccase has a very negative impact on its overall catalytic function. Despite this, we have not found evidence of structural damage by SDS-PAGE and circular dichroism experiments, which indicate that the enzyme retained its secondary structure. We believe that, given the importance of Laccase in environmental bioremediation, the information found about the stability of this kind of biomolecule exposed to UV solar irradiation may be relevant in the technological design and/or optimization of decontamination strategies.

中文翻译：

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UVB太阳辐射对漆酶的影响：光氧化过程的评估及其对污染物生物修复酶活性的影响。

多铜漆酶对应于在异源生物修复中潜在用途的研究最多的氧化还原酶之一。在这项工作中，我们研究了从Trametes versicolor的漆酶的光降解过程由UVB光引起的紫外线辐射及其对选定基材上活性的影响。漆酶在受到UVB光照射后会发生光降解，其过程取决于介质中氧气的存在。利用从静态和时间分辨测量获得的动力学数据，提出了酶的光敏性自敏化机理。漆酶通过UVB光吸收产生单线态氧，而这种活性氧可以触发蛋白质结构中易感氨基酸残基的光氧化。在UVB光解之前和之后，评估漆酶对代表潜在污染物的羟基芳族化合物和取代酚的催化活性。染料溴百里酚蓝，抗生素利福平和模型化合物丁香嗪，被选为基材。在我们的实验中确定的动力学参数值表明，漆酶的光氧化过程对其整体催化功能有非常不利的影响。尽管如此，我们还没有发现通过SDS-PAGE和圆二色性实验发现结构破坏的证据，这表明该酶保留了其二级结构。我们认为，鉴于漆酶在环境生物修复中的重要性，有关这种暴露于紫外线太阳光下的生物分子的稳定性的信息可能与去污策略的技术设计和/或优化有关。尽管如此，我们仍未通过SDS-PAGE和圆二色性实验发现结构受损的证据，这表明该酶保留了其二级结构。我们相信，鉴于漆酶在环境生物修复中的重要性，有关这种暴露于紫外线太阳光下的生物分子的稳定性的信息可能与去污策略的技术设计和/或优化有关。尽管如此，我们仍未通过SDS-PAGE和圆二色性实验发现结构受损的证据，这表明该酶保留了其二级结构。我们相信，鉴于漆酶在环境生物修复中的重要性，有关这种暴露于紫外线太阳光下的生物分子的稳定性的信息可能与去污策略的技术设计和/或优化有关。