Artificial Peroxidase/Oxidase Multiple Enzyme System Based on Supramolecular Hydrogel and Its Application as a Biocatalyst for Cascade Reactions

Inspired by delicate structures and multiple functions of natural multiple enzyme architectures such as peroxisomes, we constructed an artificial multiple enzyme system by coencapsulation of glucose oxidases (GOx) and artificial peroxidases in a supramolecular hydrogel. The artificial peroxidase was a functional complex micelle, which was prepared by the self-assembly of diblock copolymer and hemin. Compared with catalase or horseradish peroxidase (HRP), the functional micelle exhibited comparable activity and better stability, which provided more advantages in constructing a multienzyme with a proper oxidase. The hydrogel containing the two catalytic centers was further used as a catalyst for green oxidation of glucose, which was a typical cascade reaction. Glucose was oxidized by oxygen (O₂) via the GOx-mediated reaction, producing toxic intermediate hydrogen peroxide (H₂O₂). The produced H₂O₂ further oxidized peroxidase substrates catalyzed by hemin-micelles. By regulating the diffusion modes of the enzymes and substrates, the artificial multienzyme based on hydrogel could successfully activate the cascade reaction, which the soluble enzyme mixture could not achieve. The hydrogel, just like a protective covering, protected oxidases and micelles from inactivation via toxic intermediates and environmental changes. The artificial multienzyme could efficiently achieve the oxidation task along with effectively eliminating the toxic intermediates. In this way, this system possesses great potentials for glucose detection and green oxidation of a series of substrates related to biological processes

Effect of the Surface Charge of Artificial Chaperones on the Refolding of Thermally Denatured Lysozymes

Artificial chaperones are of great interest in fighting protein misfolding and aggregation for the protection of protein bioactivity. A comprehensive understanding of the interaction between artificial chaperones and proteins is critical for the effective utilization of these materials in biomedicine. In this work, we fabricated three kinds of artificial chaperones with different surface charges based on mixed-shell polymeric micelles (MSPMs), and investigated their protective effect for lysozymes under thermal stress. It was found that MSPMs with different surface charges showed distinct chaperone-like behavior, and the neutral MSPM with PEG shell and PMEO₂MA hydrophobic domain at high temperature is superior to the negatively and positively charged one, because of the excessive electrostatic interactions between the protein and charged MSPMs. The results may benefit to optimize this kind of artificial chaperone with enhanced properties and expand their application in the future