Peculiarities of alkylamidopropyldimethylbenzylammonium (Miramistin) in the relationship to lysozyme in comparison with quaternary ammonium surfactants: Coadsorption at the interfaces, enzymatic activity and molecular docking

Benzyldimethyl[3-[(1-oxotetradecyl)amino]propyl]ammonium chloride available as Miramistin is an effective antimicrobial agent, but its colloidal properties and interaction with proteins are not studied well. In present work we compared Miramistin with series of alkyltrimethylammonium bromides (DTAB, TTAB and CTAB) in the relationship to lysozyme. Complex analysis including coadsorption at the aqueous-air and aqueous-organic liquid interfaces, protein intrinsic fluorescence and enzymatic activity of lysozyme in the presence of surfactants was performed. By means of radiochemical and spectroscopic methods we have shown that cationic surfactants form complexes with lysozyme at the interfaces as well as in the bulk of the solution. Lysozyme and cationic surfactants replace each other in the adsorption layer. Miramistin binds to lysozyme surface as well as to its active site with high efficiency like surfactant with short hydrocarbon moiety (DTAB), nevertheless, it possesses low value of critical micelle concentration like CTAB. Quaternary ammonium surfactants increase enzymatic activity of lysozyme: Miramistin enhances the activity intensively then all alkyltrimethylammonium bromides. This result is explained by docking results indicated that in the case of Miramistin Asp52 residue does not form bond with the ligand unlike the cases with other alkyltrimethylammonium bromides.