The oxidase-like activity of hemin encapsulated by single-ring GroEL mutant and its application for colorimetric detection
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Supramolecular anchoring of metalloporphyrins in a protein is an attractive approach to the generation of artificial enzymes. Here, we employ the hydrophobic nanocage of single-ring mutant of bacterial GroEL protein for this purpose. We found that multiple monomeric hemin cofactors can be efficiently loaded into the protein nanocage. The as-prepared biohybrid possessed an oxidase-like catalytic activity and followed the typical Michaelis–Menten kinetics and a ping-pong mechanism in the H2O2-mediated oxidation of model substrates. In comparison with natural peroxidase, the artificial enzyme exhibited higher affinity for the model substrate. A simple and sensitive colorimetric method for the quantitative detection of H2O2 and glucose was also developed based on the artificial enzyme, with the detection limits determined to be 3.0 μM for H2O2 and 5.0 μM for glucose, respectively. The protein nanocage-based artificial enzyme is very flexible and is envisioned to be adapted readily for binding other metal complexes and catalysis of other reactions.
This work was supported by the National Natural Science Foundation of China (21503278) and the Fundamental Research Funds for the Central Universities.
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