Periodate oxidized glucose oxidase@ZIF-8 nanocomposite

Abstract

The durability of enzymes in harsh conditions can be enhanced by immobilization within metal-organic frameworks(MOFs) via a process called biomimetic mineralisation. Zeolitic imidazolate framework-8 (ZIF-8) is widely used as aprotective coating to encapsulate proteins. The formation of nucleation centres and further biocomposite particlegrowth is entirely governed by the pure electrostatic interactions between the protein’s surface and positively chargedZn(II) metal ions. It was previously shown that enhancing these electrostatic interactions by a chemical modificationof surface amino acid residues can lead to a rapid biocomposite formation. However, a chemical modification ofcarbohydrate components by periodate oxidation for glycoproteins can serve as an alternative strategy. In the presentstudy, an industrially important enzyme glucose oxidase (GOx) was selected as a model system. Periodate oxidationof GOx by 2.5 mM sodium periodate increased negative charge on the enzyme molecule. Biomineralizationexperiments with oxidized GOx resulted in higher specific activity, effectiveness factor, and higher thermostability ofthe ZIF-8 biocomposites.