Impact of [formula omitted] on the thermophysical and FTIR properties of protein model compounds in aqueous solutions

Abstract

Ionic liquids (ILs) have gained popularity in recent years due to their wide range of applications in chemical synthesis. They can be used in advancing technologies such as protein solubilization, increased protein activity, biocatalysis replication, and enzyme stability. Because of this, ILs can shed light on the ability of proteins to maintain stability. The present paper outlines the impact of IL on the thermophysical and FTIR properties of specific protein model compounds in aqueous solutions. Thus, densities ρand viscosities ηof some protein model compounds in aqueous solutions of ionic liquid, 1-butyl-3-methylimidazolium chloride, BMImCl, at various temperatures have been carried out at atmospheric pressure. These studies are aimed at gaining new insights into the ability of biomolecules to interact with IL, which is critical for understanding protein behaviour in solutions.Various parameters such as apparent molar volumes (V∅), partial molar volumes (V2O), viscosity B-coefficients, temperature coefficients (dB/dT), transfer parameters, i.e.,ΔtrV2o and ΔtrB, interaction parameters,YAB and YABB, hydration number i.e.nH and Nh, partial molar expansibilities ∂V2O/∂TP, their second-order derivatives ∂2V2O/∂T2P, and isobaric thermal expansion coefficients (αIL) have been calculated from density and viscosity data. In aqueous BMImCl, partial molar expansibilities and temperature coefficients are used to predict the structure maker/breaker behaviour of amino acids. Volume transfer values indicate the dominance of ionic-hydrophilic interactions. Thermodynamic parameters suggest that the formation of the transition state is less favoured in the presence of BMImCl solutions. Also, the effects of the hydrophilic ionic liquid, 1-butyl-3-methylimidazolium chloride,BMImCl on the ion-hydrophilic, hydrophobic-hydrophilic, and hydrophobic-hydrophobic interactions present in ternary systems, as well as the effects of temperature and alkyl chain length, have been discussed. FTIR spectra were measured to analyze the structural changes that occurred in the system. The current work provides some important fundamental experimental data and theoretical support for further exploring the interactions of various amino acids with ILs.