Spectroscopic and molecular docking studies of the interaction between meloxicam and pepsin

In order to study the interaction mechanism between meloxicam and pepsin, the interaction between meloxicam and pepsin was studied by fluorescence spectroscopy, UV-visible absorption spectroscopy, circular dichroism spectroscopy and molecular docking under physiological conditions (pH = 2.20). The results of spectral experiments showed that meloxicam quenched the intrinsic fluorescence of pepsin by static quenching, formed a stable complex at 1:1, and changed the conformation of pepsin. The thermodynamic results showed that the main force type of meloxicam and pepsin system was hydrophobic interaction. Molecular docking showed that there was a hydrogen bond in addition to hydrophobic interaction, and the best binding site between meloxicam and pepsin was near the catalytic active center of pepsin. The results showed that the combination of the meloxicam and pepsin changed the microenvironment of amino acid residues at the catalytic active center of pepsin. Under the experimental conditions, the protein binding rate of meloxicam to pepsin W(B) was 2.97–48.3%, indicating that the binding of meloxicam to pepsin had an effect on the number of free pepsin. The drug binding rate of the system W(Q) was 2.97–1.39%, indicating that the binding effect of meloxicam and pepsin on the number of free drug molecules was weak, so the binding effect would not have a significant effect on the efficacy of meloxicam.