尽管金属有机框架(MOFs)被认为是有前途的酶固定化基质,HKUST-1,由乙酸铜(CuAc2)和1,3,5-三羧酸苯(BTC)制成,很少对此应用程序进行探索。在这项研究中,蘑菇酪氨酸酶(EC1.14.18.1)以酪氨酸酶@HKUST-1的形式固定,这是通过在添加CuAc2之前将BTC与酶混合进行的简单反应程序。所得到的生物催化剂在结构特征和催化性能方面都进行了表征。在纳入HKUST-1框架后,该酶对pH的稳定性有了显著的增强,温度和储存:当在50°C和pH6.0下孵育时,酪氨酸酶@HKUST-1的半衰期为32.6h,比游离酶和其他固定化形式高77倍甚至10倍,当在30°C下储存时,催化剂的活性完全保持至少2个月。通过将其用作区域选择性邻位羟基化反应的催化剂,以产生具有巨大药理作用的儿茶酚产物,证明了这种新型生物催化剂的适用性。即,羟基酪醇和L-DOPA,具有优异的产量和生产率。因此,本研究提供了一种简便的固定化方法来制备具有超稳定性的新型生物催化剂,和酪氨酸酶@HKUST-1这样形成的粗蘑菇提取物提供了一种有效的催化剂,可用于生产具有健康益处的儿茶酚酸产品。
Although metal-organic frameworks (MOFs) have been considered as promising matrices for enzyme immobilization, HKUST-1, constructed from copper acetate (CuAc2) and benzene 1,3,5-tricarboxylate (BTC), has rarely been explored for this application. In this study, mushroom
tyrosinase (EC 1.14.18.1) was immobilized in the form of
tyrosinase@HKUST-1 following a simple reaction procedure by mixing BTC with the enzyme prior to addition of CuAc2. The resultant biocatalyst was characterized in both structural features and catalytic properties. Upon incorporation into the HKUST-1 frameworks, the enzyme gained a prominent enhancement in stability against pH, temperature and storage: When incubated at 50 °C and pH 6.0,
tyrosinase@HKUST-1 presented a half-life of 32.6 h, which is 77-fold and over tenfold higher than that of the free enzyme and its other immobilization forms, respectively; and the catalyst fully maintained its activity for at least 2 months when stored at 30 °C. The applicability of this new biocatalyst was demonstrated by employing it as catalyst for regioselective ortho-hydroxylation reactions to produce catecholic products with huge pharmacological effects, i.e., hydroxytyrosol and L-DOPA, with excellent yields and productivities. This study has thus offered a facile immobilization method to prepare a novel biocatalyst with super stability, and
tyrosinase@HKUST-1 so formed from crude mushroom extract provides an efficient catalyst which can be applied to the production of catecholic products with health benefits.