Improving thermostability, solvent tolerance, and reusability of methyl parathion hydrolase through immobilization into the metal-organic framework ZIF-8

Abstract

The metal-organic framework (MOF) ZIF-8 has found extensive application in the medicinal and agricultural fields. This study aimed to immobilize the methyl parathion hydrolase (MPH) enzyme from Azohydromonas australica (Azau-MPH) within ZIF-8 using an in-situ synthesis method. Interestingly, the immobilized Azau-MPH (abbreviated as Azau-MPH@ZIF-8) exhibited enhanced thermostability and tolerability towards organic solvents compared to the free enzyme. Moreover, Azau-MPH@ZIF-8 retained more than 50% of its initial activity after six cycles, demonstrating its desirable reusability. To further improve the recyclability and catalytic activity of the immobilized enzyme, we introduced magnetic Fe3O4 nanoparticles into the immobilization carrier. Notably, the resulting Azau-MPH@(Fe3O4@ZIF-8) biocomposite displayed superior catalytic activity and stability when compared to Azau-MPH@ZIF-8. In practical applications, we employed Azau-MPH@ZIF-8 for cyclic degradation of methyl parathion (20 mg/L) in cherries, and it exhibited exceptional degradation ability. Hence, both Azau-MPH@ZIF-8 and Azau-MPH@(Fe3O4@ZIF-8) hold great promise as valuable biodegradation tools against MP contamination.