Characterization of the Interactions between Minocycline Hydrochloride and Trypsin with Spectroscopic and Molecular...

In the current study, the interaction of minocycline hydrochloride (MC) and trypsin (TRP) was studied using fluorescence spectroscopy, synchronous fluorescence spectroscopy, three-dimensional fluorescence spectroscopy, UV-Vis spectroscopy, and molecular docking simulation techniques. The results show that the fluorescence quenching of trypsin at different degrees can be caused by minocycline hydrochloride at different temperatures. According to the Stern-Volmer equation, the fluorescence quenching type was static quenching. By calculating critical distance, we concluded that there is a possibility of non-radiative energy transfer between minocycline hydrochloride and trypsin. The effect of minocycline hydrochloride on the secondary structure of trypsin was demonstrated using ultraviolet spectroscopy. Synchronous fluorescence spectroscopy showed that minocycline hydrochloride could bind to tryptophan residues in trypsin, resulting in corresponding changes in the secondary structure of trypsin. Three-dimensional fluorescence spectroscopy showed that minocycline hydrochloride had a particular effect on the microenvironment of trypsin that led to changes in the secondary structure of trypsin. The molecular docking technique demonstrated that the binding of minocycline hydrochloride and trypsin was stable. Circular dichroism showed that the secondary structure of trypsin could be changed by minocycline hydrochloride.