Comparative effect of cationic gemini surfactant and its monomeric counterpart on the conformational stability and activity of lysozyme

Abstract

Protein interactions with surfactants are dependent on their physiochemical properties. The effect of cationic gemini surfactant hexanediyl-a,u-bis-(N-(2-hydroxyethyl)-N-methylhexadecylammonium dibromide) on the stability and activity of hen egg white lysozyme was compared with its monomeric counterpart N-(2-hyroxyethyl)-N,N-dimethylhexadecylammonium bromide at pre and post micellar concentrations. This study utilizes circular dichroism (CD), steady-state fluorescence spectroscopy, extrinsic fluorescence spectroscopy, time-resolved fluorescence spectroscopy, UV-visible spectroscopy, molecular docking and turbidity assays to resolve the conformational stability and antibacterial activity of lysozyme in the presence of surfactants. Micelles of both cationic surfactants were observed to stabilize the conformation of the protein, however, gemini was found to stabilize it in a much higher micellar concentration range. Detailed analysis of the time-resolved fluorescence spectroscopy results suggests contribution of the lifetime values of Trp62 and Trp108 to the overall conformation change of lysozyme with the increase in concentration of the respective surfactants, which is further correlated with the steady-state fluorescence and CD spectroscopy results. Furthermore, from the CD analysis it was found that the cationic single chain surfactant strongly perturbs the secondary and tertiary structure of the protein as compared to the gemini surfactant. Through docking results, it was found that the gemini surfactant binds weakly with lysozyme as compared to the single chain surfactant. Specifically, the antibacterial activity of lysozyme was found to be increased in the presence of cationic gemini surfactant, which extrapolates the use of these surfactants in pharmaceutics and industries. Scheme 1 Structure of N-(2-hydroxyethyl)-N,N-dimethylhexadecyl ammonium bromide (M 16 ) and hexanediyl-a,u-bis-N-(2-hydroxyethyl)-N-methylhexadecyl ammonium dibromide (G 16 ). Scheme 2 Scheme showing the interaction pattern of M 16 and G 16 with lysozyme before and after CMC.

Esterase activity and conformational changes of bovine serum albumin toward interaction with mephedrone: Spectroscopic and computational studies

“…Lifetime measurements gather valuable information about conformational multifariousness of proteins. The folding/unfolding conditions prevailed largely due to the extent of solvent accessibility, and several local configurations of proteins determine the contribution of respective components . Interaction of Trp residues in protein with the local environment and the solvent assimilates to provide the fluorescence lifetime.…”

Study of metal-lipopeptide complexes and their self-assembly behavior, micelle formation, interaction with bovine serum albumin and biological properties

“…Fluorescence quenching can occur through dynamic and static mechanisms [45]. The involvement of two types of quenching mechanism, dynamic and static can be distinguished by the temperature dependent behavior of their Stern-Volmer quenching constants (K SV ).…”

“…The involvement of two types of quenching mechanism, dynamic and static can be distinguished by the temperature dependent behavior of their Stern-Volmer quenching constants (K SV ). The K SV values decrease with an increase in temperature for static quenching, but the reverse effect will be observed for dynamic quenching [45]. In order to evaluate the mode of quenching, the Stern-Volmer equation (Eq.…”

Probing the Intercalation of Noscapine from Sodium Dodecyl Sulfate Micelles to Calf Thymus Deoxyribose Nucleic Acid: A Mechanistic Approach

“…Time-resolved fluorescence decay is a very sensitive tool for studying the nature of hydration as well as the relaxation dynamics of the drug in aqueous and micellar environments and also the excited state interactions of the probe. ,− This gives the information about the residence of the probe within different micro heterogeneous mediums. Herein, we observe the fluorescence lifetime of NOS in different environments to find out its replacement from micelles to the ctDNA in the composite medium.…”