Unveiling the thermodynamic signature underlying the interaction of human serum albumin with sub-micellar concentrations of a surface active ionic liquid

Exploring Biophysical and Chemoinformatics Approaches for Interactions of Ionic Liquids With Hemoglobin, DNA, BSA, and HSA

This review article provides an inclusive overview of the intricate interactions amid ionic liquids (ILs) and essential biomacromolecules, mainly hemoglobin (Hb), bovine serum albumin (BSA), human serum albumin (HSA), and calf thymus-DNA (CT-DNA). ILs have recently become a topic of great attention because of their inimitable physicochemical properties and potential uses in different fields. The review systematically explores the binding mechanisms, thermodynamics, and structural changes induced by ILs on Hb, BSA, HSA, and CT-DNA using spectroscopic, thermodynamic, and computational techniques. The article highlighted various experimental and computational methodologies to explore the interactions between ILs and biomacromolecules. It offers an in-depth analysis of the techniques employed to decode the intricate nature of these molecular associations and the influence of ILs along with their structural characteristics on the conformational stability, activity, and functionality of biomacromolecules. This foundational understanding is essential for advancing research and developing strategies that exploit the distinctive properties of ILs to foster innovative and sustainable applications within the biomedical field.

pH-Induced Biophysical Perspectives of Binding of Surface-Active Ionic Liquid [BMIM][OSU] with HSA and Dynamics of the Formed Complex

The influence of pH on the human serum albumin (HSA) interaction with ionic liquid (IL)1-butyl 3-methylimidazolium octyl sulfate ([BMIM][OSU]) at its sub-micellar concentration of 5 mM (well below CMC ∼31 mM at 25 °C) in aqueous solution has been monitored employing different methods, viz., circular dichroism (CD), fluorescence, electrokinetic determination of the zeta potential (ZP), nuclear magnetic resonance (NMR), small-angle neutron scattering (SANS), and molecular docking (MD). CD analysis indicated a noticeable reduction of the α-helical content of HSA by IL at pH 3. A significant interaction of the anionic part of IL with HSA was evident from the ¹H chemical shifts and saturation transfer difference (STD) NMR. A strong binding between IL and HSA was observed at pH 3 relative to pH 5, revealing the importance of electrostatic and hydrophobic interactions assessed from global binding affinities and molecular correlation times derived from STD NMR and a combined selective/nonselective spin-relaxation analysis, respectively. ZP data supported the electrostatic interaction between HSA and the anionic part of IL. The nature of IL self-diffusion with HSA was assessed from the translational self-diffusion coefficients by pulse field gradient NMR. SANS results revealed the formation of prolate ellipsoidal geometry of the IL-HSA complex. MD identified the preferential binding sites of IL to the tryptophan centers on HSA. The association of IL with HSA was supported by fluorescence measurements, in addition to the structural changes that occurred in the protein by the interaction with IL. The anionic part of IL contributed a major interaction with HSA at the pH levels of study (3, 5, 8, and 11.4); at pH > 8 (effectively 11.4), the protein also interacted weakly with the cationic component of IL.