Comparison of the interactions of fanetizole with pepsin and trypsin: Spectroscopic and molecular docking approach

In this work, the binding affinity of fanetizole with proteases pepsin and trypsin were investigated by spectroscopy and molecular docking. As a thiazole derivative, the interactions of fanetizole with either pepsin or trypsin resulted in a fluorescence quenching. As such, the calculated values of K manifested that the fanetizole-pepsin system has a stronger binding affinity than fanetizole-trypsin at 296 K. Moreover, steady-state, time-resolved fluorescence and thermodynamic studies of the interaction of fanetizole with pepsin or trypsin suggested that a static fluorescence quenching mechanism and the interactions were primarily attributed to hydrogen-bonding interaction. The observed changes in synchronous fluorescence, circular dichroism spectroscopy, and FTIR results were related to the secondary construction alternations of both proteases. In line with fluorescence spectroscopy, molecular docking demonstrated similar binding characteristics and domains. The range of r values showed energy transfer from pepsin/trypsin to fanetizole.