Neeraj Dohare

Molecular investigation of the interaction between ionic liquid type gemini surfactant and lysozyme: A spectroscopic and computational approach

Herein, we are reporting the interaction of ionic liquid type gemini surfactant, 1,4‐bis(3‐dodecylimidazolium‐1‐yl) butane bromide ([C12−4‐C12im]Br2) with lysozyme by using Steady state fluorescence, UV‐visible, Time resolved fluorescence, Fourier transform‐infrared (FT‐IR) spectroscopy techniques in combination with molecular modeling and docking method. The steady state fluorescence spectra suggested that the fluorescence of lysozyme was quenched by [C12−4‐C12im]Br2 through static quenching mechanism as confirmed by time resolved fluorescence spectroscopy. The binding constant for lysozyme‐[C12−4‐C12im]Br2 interaction have been measured by UV‐visible spectroscopy and found to be 2.541 × 105M−1. The FT‐IR results show conformational changes in the secondary structure of lysozyme by the addition of [C12−4‐C12im]Br2. Moreover, the molecular docking study suggested that hydrogen bonding and hydrophobic interactions play a key role in the protein‐surfactant binding. Additionally, the molecular dynamic simulation results revealed that the lysozyme‐[C12−4‐C12im]Br2 complex reaches an equilibrium state at around 3 ns.

Effect of 1-methyl-3-octyleimmidazolium chloride on the stability and activity of lysozyme: a spectroscopic and molecular dynamics studies

Herein, the binding of 1-methyl-3-octylimidazolium chloride [OMIM][Cl] ionic liquid with hen egg white lysozyme (HEWL) has been studied using fluorescence, time resolved fluorescence, UV–visible and circular dichroism (CD) spectroscopy, in combination with computational study. The fluorescence results revealed that [OMIM][Cl] quenches the fluorophore of HEWL through static quenching mechanism. The calculated thermodynamic parameters show that [OMIM][Cl] bind with HEWL through hydrophobic interactions. In addition, the negative value of Gibbs energy change (∆G) indicates that the binding process was spontaneous. Furthermore, UV–vis and CD results indicate that [OMIM][Cl] induce the conformational change in HEWL and increase its enzymatic activity. Additionally, molecular docking results showed that [OMIM][Cl] binds at the active site of HEWL where both the fluorophore residues (Trp108 and Trp62) and the catalytic residues (Glu35 and Asp52) reside. Molecular dynamic simulation results show the reduction of intra-molecular hydrogen bond of HEWL when it binds with [OMIM][Cl].

A spectroscopic and molecular dynamic approach on the interaction between ionic liquid type gemini surfactant and human serum albumin.

The interactions of imidazolium bashed ionic liquid-type cationic gemini surfactant ([C12-4-C12im]Br2) with HSA were studied by fluorescence, time-resolved fluorescence, UV-visible, circular dichroism, molecular docking and molecular dynamic simulation methods. The results showed that the [C12-4-C12im]Br2 quenched the fluorescence of HSA through dynamic quenching mechanism as confirmed by time-resolved spectroscopy. The Stern–Volmer quenching constant (Ksv) and relevant thermodynamic parameters such as enthalpy change (ΔH), Gibbs free energy change (ΔG) and entropy change (ΔS) for interaction system were calculated at different temperatures. The results revealed that hydrophobic forces played a major role in the interactions process. The results of synchronous fluorescence, UV-visible and CD spectra demonstrated that the binding of [C12-4-C12im]Br2 with HSA induces conformational changes in HSA. Inquisitively, the molecular dynamics study contribute towards understanding the effect of binding of [C12-4-C12im]Br2 on HSA to interpret the conformational change in HSA upon binding in aqueous solution. Moreover, the molecular modelling results show the possible binding sites in the interaction system.

Effect of pyrrolidinium based ionic liquid on the channel form of gramicidin in lipid vesicles

The present work is focused on the interaction between membrane bound gramicidin and 1-butyl-1-methyl-2-oxopyrrolidinium bromide (BMOP) ionic liquid. Ionic liquids (ILs) are solvents that are often liquid at room temperature and composed of organic cation and appropriate anion. The gramicidin peptide forms prototypical ion channels for cations, which have been extensively used to study the organization, dynamics, and function of membrane spanning channels. The interaction was studied by circular dichroism, steady state, time-resolved fluorescence spectroscopy in combination with dynamic surface tension and field emission scanning electron microscopic methods (FESEM). The results obtained from circular dichroism shows that the BMOP interacts with the channel form of gramicidin in lipid vesicle without any considerable effect on its conformation. The Red-edge excitation shift (REES) also supported the above findings. In addition, the fluorescence studies suggested that BMOP makes ground state complex with ion channel, which was further supported by time resolved measurements. Furthermore, dynamic surface tension analysis shows the faster adsorption of BMOP with membrane bound gramicidin at the air-water interface. Additionally, FESEM results indicated that BMOP forms a film around the membrane bound gramicidin at higher concentration. These results are potentially useful to analyze the effect of ionic liquids on the behaviour of membrane proteins.

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

Protein interactions with surfactants are dependent on their physiochemical properties. The effect of cationic gemini surfactant hexanediyl-α,ω-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.

Enthalpy-driven interaction between dihydropyrimidine compound and bovine serum albumin: a spectroscopic and computational approach

Diazines represent an important class of heterocyclic compounds, which are known to exhibit a wide spectrum of biological activities, and the majority of these versatile compounds are the backbone ...

Urea-induced binding between diclofenac sodium and bovine serum albumin: a spectroscopic insight.

We investigated the interaction of diclofenac sodium (Dic.Na) with bovine serum albumin (BSA) in the absence and presence of urea using different spectroscopic techniques. A fluorescence quenching study revealed that the Stern-Volmer quenching constant decreases in the presence of urea, decreasing further at higher urea concentrations. The binding constant and number of binding sites were also evaluated for the BSA-Dic.Na interaction system in the absence and presence of urea using a modified Stern-Volmer equation. The binding constant is greater at high urea concentrations, as shown by the fluorescence results. In addition, for the BSA-Dic.Na interaction system, a static quenching mechanism was observed, which was further confirmed using time-resolved fluorescence spectroscopy. UV-vis spectroscopy provided information about the formation of a complex between BSA and Dic.Na. Circular dichroism was carried out to explain the conformational changes in BSA induced by Dic.Na in the absence and presence of urea. The presence of urea reduced the α-helical content of BSA as the Dic.Na concentration varied. The distance r between the donor (BSA) and acceptor (Dic.Na) was also obtained in the absence and presence of urea, using fluorescence resonance energy transfer. Copyright

An insight into the binding of aceclofenac with bovine serum albumin at physiological condition: a spectroscopic and computational approach

An insight into the binding of aceclofenac with bovine serum albumin at physiological condition: a spectroscopic and computational approach Neeraj Dohare, Abbul Bashar Khan, Neha Maurya, Sonu Thakur, Fareeda Athar, Prashant Singh and Rajan Patel* Biophysical Chemistry Laboratory, Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia (A Central University), New Delhi, India; Department of Chemistry, A. R. S. D. College, University of Delhi, Delhi 110021, India

Interaction between Pyrrolidinium Based Ionic Liquid and Bovine SerumAlbumin: A Spectroscopic and Molecular Docking Insight

Herein, we report the interaction of N, N-dimethyl-2-oxopyrrolidinium iodide with bovine serum albumin by using steady-state fluorescence, time-resolved fluorescence, UV-visible and Fourier Transform-Infrared spectroscopy in combination with molecular docking method. The steady state fluorescence spectra results confirmed that N, N-dimethyl- 2-oxopyrrolidinium iodide strongly quenches the intrinsic fluorescence of bovine serum albumin by a dynamic quenching mechanism as confirmed by time resolved fluorescence spectroscopy. The thermodynamic parameters (ΔH, ΔG and ΔS) showed that the binding process was spontaneous and enthalpy driven. Moreover, the interacting forces between bovine serum albumin and N, N-dimethyl-2-oxopyrrolidinium were mainly governed through hydrogen bond and van der Waals forces. The Fourier Transform-Infrared spectroscopy results show the conformational change of bovine serum albumin on binding with N, N-dimethyl-2-oxopyrrolidinium. Additionally, molecular modeling results revealed that N, N-dimethyl-2-oxopyrrolidinium binds with the amino acid residues of the sub domain IIA of bovine serum albumin.

Effect of aromatic amino acids on the surface properties of 1-dodecyl-3-(4-(3-dodecylimidazolidin-1-yl)butyl)imidazolidine bromide gemini surfactant

ABSTRACT Herein, we have studied the micellization of imidazolium-based ionic liquid type gemini surfactant ([C12-4-C12im]Br2) in the absence and presence of aromatic amino acids by conductivity and surface tension measurements at different temperatures (i.e., 298, 308, and 318 K). Various interfacial parameters, that is, Gibbs surface excess (Γmax), minimum head group area at air/water interface (Amin), and thermodynamic parameters, that is, free energy of micellization/adsorption (), the standard entropy of micellization/adsorption (), and the standard enthalpy of micellization/adsorption () were evaluated for all the systems. The standard entropy of adsorption () was found higher than the standard entropy of micellization () for all the systems at all temperatures. The results also showed that the micellization of [C12-4-C12im]Br2 depends on the nature of amino acids as well as temperature. The CMC of [C12-4-C12im]Br2 in the absence and presence of amino acids at different temperature decreases with the increase of temperature. GRAPHICAL ABSTRACT