Mechanism of salt-induced activity enhancement of a marine-derived laccase, Lac15
Mechanism of salt-induced activity enhancement of a marine-derived laccase, Lac15
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盐诱导海洋漆酶 Lac15 活性增强的机制
DOI：
10.1007/s00249-017-1251-5
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发表时间：
2018-04-01
影响因子：
2
通讯作者：
Xiao, Yazhong
中科院分区：
文献类型：
--
作者：
Li, Jie;Xie, Yanan;Xiao, Yazhong
漆酶（苯酐：氧氧化还原酶，EC1.10.3.2）是能够氧化多种酚类和其它芳香族有机化合物的多铜氧化酶。漆酶的催化能力使其在许多工业领域具有潜在的应用前景，包括有机污染物的生物降解和新型药物的合成。大多数漆酶易受高盐的影响，应用受到限制。然而，有些漆酶不仅耐盐，而且能被一定浓度的盐激活，因此具有很大的应用潜力。盐诱导漆酶活性增强的机制尚不清楚。在这项研究中，我们使用动态光散射，尺寸排阻色谱，分析超离心，固有荧光发射，圆二色性，紫外-可见光吸收，和酶的测定，以探讨潜在的海洋来源的漆酶，Lac 15，其活性是由低浓度的NaCl促进的结构和活性之间的相关性。结果表明，低浓度的NaCl对蛋白质结构的影响很小，在没有盐的情况下，蛋白质是部分折叠的;此外，部分折叠而不是完全折叠的状态似乎有利于酶的活性，这种部分折叠的状态与活性酶中偶尔观察到的所谓的“熔融球”不同。更多的数据表明，盐促进漆酶活性的机制可能涉及特定的局部网站的扰动，而不是在全球结构的变化。提出了氯离子的潜在结合位点及其在酶活性促进中的作用。
Laccase (benzenediol: oxygen oxidoreductases, EC1.10.3.2) is a multi-copper oxidase capable of oxidizing a variety of phenolic and other aromatic organic compounds. The catalytic power of laccase makes it an attractive candidate for potential applications in many areas of industry including biodegradation of organic pollutants and synthesis of novel drugs. Most laccases are vulnerable to high salt and have limited applications. However, some laccases are not only tolerant to but also activated by certain concentrations of salt and thus have great application potential. The mechanisms of salt-induced activity enhancement of laccases are unclear as yet. In this study, we used dynamic light scattering, size exclusion chromatography, analytical ultracentrifugation, intrinsic fluorescence emission, circular dichroism, ultraviolet-visible light absorption, and an enzymatic assay to investigate the potential correlation between the structure and activity of the marine-derived laccase, Lac15, whose activity is promoted by low concentrations of NaCl. The results showed that low concentrations of NaCl exert little influence on the protein structure, which was partially folded in the absence of the salt; moreover, the partially folded rather than the fully folded state seemed to be favorable for enzyme activity, and this partially folded state was distinctive from the so-called 'molten globule' occasionally observed in active enzymes. More data indicated that salt might promote laccase activity through mechanisms involving perturbation of specific local sites rather than a change in global structure. Potential binding sites for chloride ions and their roles in enzyme activity promotion are proposed.