Construction of metalloenzyme mimics based on self-assembled peptides

Abstract

Laccase is a natural enzyme with high catalytic activity capable of catalyzing the oxidation of many different substrates. Laccase is of great importance in lignin degradation, bioremediation, environmental protection and biocatalysis. However, in practical application scenarios, natural laccase suffers from poor stability, high preparation cost, and difficulty in large-scale production, which seriously limits the large-scale application of laccase in various industries. In this study, in order to solve the problems of poor stability and high production cost of natural laccase, a peptide sequence Ac-ICVHLHLHVHI-CONH2 was rationally designed according to the active center and structural characteristics of natural laccase, and a metal mimetic enzyme with peptide as material was successfully constructed. By examining the effects of different metal ions and different metal ion concentrations on the catalytic activity of the mimic enzyme, the results showed that Cu2+ was the most suitable metal ion for binding with the mimic enzyme, and the catalytic activity of Cu2+ was the highest for the substrate 2,4 dichlorophenol (2,4-DP) after combining with the peptide mimic enzyme when the concentration of Cu2+ was 8 mM at the pH 6. The experiments were further performed by using Circle II (CD) chromatography, Fourier (FTIR) infrared spectroscopy, and transmission electron microscopy (TEM) to characterize the structure of the mimetic enzyme, and the results proved that Cu2+ could induce the polypeptide to increase the degree of assembly, become more structurally ordered, and form an obvious β-folded secondary structure with tightly assembled aggregates. The metal-mimetic enzymes constructed in this study with peptides as materials provide a new design direction and experimental basis for applications in fields such as industrial catalysis and green chemistry.