Mushroom tyrosinase immobilized in metal-organic frameworks as an excellent catalyst for both catecholic product synthesis and phenolic wastewater treatment

BACKGROUND Metal-organic frameworks (MOFs) have gained increasing attention with ever-expanding applications. Developing new MOF-based immobilized enzymes with new applications is required, not only for demonstrating the generality and applicability of using MOFs for enzyme immobilization, but also to provide potential biocatalysts for industrial applications. To the best of the authors' knowledge, this is the first report of immobilizing mushroom tyrosinase on zeolitic imidazolate frameworks (ZIFs), with two new applications being developed. RESULTS Upon immobilization through a one-pot in situ encapsulation approach, the resultant tyrosinase@ZIF-8 was characterized in structural features and catalytic properties. It was much more stable against pH and temperature relative to the free enzyme. The new biocatalyst was highly efficient in catalyzing the synthesis of catecholic products with pharmacological benefits (l-DOPA, piceatannol and 3 '-hydroxypterostilbene) and in eliminating phenolic pollutants (phenol, p-cresol, p-chlorophenol). Excellent productivities were obtained for the synthesis of the three catecholic products (0.14, 1.38 and 1.46 g L-1 h(-1), respectively). A complete removal of the three phenolic pollutants was achieved within 2.5 h, superior to other processes mediated by the same enzyme, or others, immobilized on different supports. The reusability of the new biocatalyst can be remarkably improved by entrapment into polyvinyl alcohol-alginate gel. CONCLUSIONS Tyrosinase can be immobilized on a new type of MOF with advantages such as easy preparation and excellent catalytic performance. This novel immobilization strategy for tyrosinase offers an excellent biocatalyst potent for both catecholic product synthesis and phenolic wastewater treatment. (c) 2021 Society of Chemical Industry (SCI).

Automated summary

This study presents the first immobilization of mushroom tyrosinase on zeolitic imidazolate frameworks (ZIFs) with two new applications. The immobilized enzyme showed enhanced stability and catalytic efficiency for catecholic product synthesis and phenolic wastewater treatment, making it a promising biocatalyst for industrial applications.