Sanaz Majidi
1 
, Samaneh Rashtbari
1 , Sina Jamei
1 , Golamreza Dehghan
1* 1 Laboratory of Biochemistry and Molecular Biology, Department of Biology, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran
Abstract
Introduction: Enzyme-mimic nanomaterials, or nanozymes, have received much attention in fundamental and practical research. Laccases are crucial for environmental remediation and biotechnology. Inspired by the structure of the active site and the electron transfer mechanism of laccase, a simple laccase-like platform was designed in this work.
Methods: In this work, ovalbumin (OVA) was isolated and purified from hen egg white and conjugated with the transition metal ion (Cu2+), resulting in a soluble biopolymer (OVA‒Cu complex). Using a colorimetric method based on guaiacol oxidation, the catalytic performance of the complex was assessed, and its laccase‒like activity was verified.
Results: The kinetic parameters (Km and Vmax values) of the laccase‒mimic complex were calculated to be 0.026 mM and 0.7 μM min-1, respectively. The prepared complex showed excellent catalytic activity with a similar Km value to the natural laccase enzyme at the same mass concentration. Analysis of the synthesized system's capacity to decolorize malachite green (MG) showed its strong decolorizing potential. The outcomes demonstrated that MG can be degraded up to 84% in the presence of the OVA‒Cu complex in one hour. The decolorization metabolites were tested for toxicity against Escherichia coli and Staphylococcus aureus. The results demonstrated that less hazardous metabolites were produced after degrading MG by the OVA‒Cu complex. In addition, a 5:3:1 artificial neural network (ANN) was created to predict the decolorization efficiency (DE (%)) of MG.
Conclusion: Based on these results, it is evident that the OVA‒Cu complex has the potential to take the role of natural laccases in a variety of biosensing, environmental protection, and biotechnology applications.