Catechol derivatives interact with lysozyme: correlation of noncovalent interactions and antibacterial properties

The noncovalent interaction mechanism of catechol derivatives and lysozyme (LYS) and the antibacterial property of the binding complexes were investigated in present study. The fluorescence quenching results indicated that 1-monocaffeoyl glycerol (1-MCG) and caffeic acid (CA) interacted with LYS spontaneously and the high affinity (with K a approximately 2.5 × 10 4 (mol/L) -1 and 3.1 × 10 4 (mol/L) -1 ) driven predominantly by hydrophobic forces. The secondary structure assays demonstrated the decreasing the α-helix content by 1.5% while increasing the hydrophilicity around Tyr and Trp residues. Analysis of the non-covalent interactions revealed that 1-MCG binds to LYS at multiple sites and with greater strength compared to CA. Furthermore, three G+ bacteria and three G- bacteria were applied to elucidate the antibacterial properties of the binding complexes. The 1-MCG-LYS complex demonstrated superior antibacterial activity, reducing the Minimum Inhibitory Concentration (MIC) against E. coli and S. aureus by 50% to 75% compared to LYS or 1-MCG alone. These results illuminate that the interaction between catechol derivatives and LYS, particularly the enhanced binding afforded by the glycerol side chain of 1-MCG, can significantly modulate the antibacterial efficacy of the protein, offering a promising strategy for developing novel antimicrobial complexes.