Fujian Key Laboratory of Marine Enzyme Engineering, Fuzhou University, Fujian, 350116, China.
Technical Center, Fujian Entry-Exit Inspection and Quarantine Bureau, Fuzhou, Fujian, 350001, China.
Sci Rep. 2017 Nov 27;7(1):16429. doi: 10.1038/s41598-017-16771-x.
Laccases are polyphenol oxidases with widespread applications in various industries. In the present study, the laccase from Cerrena sp. HYB07 was immobilized with four methods, namely entrapment in alginate, covalently binding to chitosan as well as formation of cross-linked enzyme aggregates (CLEAs) and magnetic CLEAs (M-CLEAs). The activity recovery rates of the immobilized laccases ranged from 29% to 68%. Immobilization elevated the reaction temperature optimum and reduced substrate specificity, but not necessarily the turnover rate. pH stability of immobilized laccases was improved compared with that of the free laccase, especially at acidic pH values. Thermal inactivation of all laccases followed a simple first-order exponential decay model, and immobilized laccases displayed higher thermostability, as manifested by lower thermal inactivation rate constants and longer enzyme half-life time. Operational stability of the immobilized laccase was demonstrated by decolorization of the triphenylmethane dye malachite green (MG) at 60 °C. MG decolorization with free laccase was accompanied by a shift of the absorption peak and accumulation of a stable, colored intermediate tetradesmethyl MG, probably due to lower thermostability of the free laccase and premature termination of the degradation pathway. In contrast, complete decolorization of MG was achieved with laccase CLEAs at 60 °C.
漆酶是多酚氧化酶，在各个行业中有广泛的应用。在本研究中，使用四种方法对 Cerrena sp. HYB07 的漆酶进行了固定化，分别是包埋在藻酸钠中、共价结合到壳聚糖上以及交联酶聚集体（CLEAs）和磁性交联酶聚集体（M-CLEAs）的形成。固定化漆酶的活性回收率范围为 29%至 68%。固定化提高了反应温度的最佳值并降低了底物特异性，但不一定提高了周转率。与游离漆酶相比，固定化漆酶的 pH 稳定性得到了提高，尤其是在酸性 pH 值下。所有漆酶的热失活动力学遵循简单的一级指数衰减模型，固定化漆酶表现出更高的热稳定性，表现为更低的热失活速率常数和更长的酶半衰期。在 60°C 下对三苯基甲烷染料孔雀石绿（MG）的脱色证明了固定化漆酶的操作稳定性。游离漆酶对 MG 的脱色伴随着吸收峰的移动和稳定的有色中间产物十四甲基 MG 的积累，这可能是由于游离漆酶的热稳定性较低，降解途径过早终止。相比之下，在 60°C 下使用漆酶 CLEAs 可以完全脱色 MG。
