Interaction of 2,2,2-trifluoroethanol with proteins: calorimetric, densimetric and surface tension approach

Abstract

The thermal denaturation of hen egg-white lysozyme was studied in the presence of 2,2,2-trifluoroethanol (TFE) at various pH values using micro differential scanning calorimetry. Quantitative thermodynamic parameters accompanying the thermal transitions were evaluated. It is observed that thermal unfolding of lysozyme in the presence of TFE upto a concentration of 4.0 mol dm follows a two-state denaturation mechanism as indicated by the equality y3 of van't Hoff and calorimetric enthalpies. The finer details of interaction were studied by measuring the partial molar volume of some constituent amino acids and glycine peptides from water to aqueous TFE at 298.15 K. The physicochemical properties of aqueous TFE: apparent molar heat capacities, apparent molar volumes and surface tension were measured to understand the intrinsic properties of the cosolvent as well. From the correlation among the thermal unfolding data on lysozyme in aqueous TFE, calculated preferential interaction parameters, physico chemical properties of aqueous TFE and partial molar volumes of transfer, it is concluded that both solvent mediated effect and direct interaction constitute the mechanism of TFE-protein interactions.

Does the anesthetic 2,2,2‐trifluoroethanol interact with bovine serum albumin by direct binding or by solvent‐mediated effects? A calorimetric and spectroscopic investigation

“…Recently it has been proposed that TFE acts by selectively desolvating the peptide backbone groups of the helix and thereby inducing the helical state. 46 Based upon calorimetric, densimetric, and surface tension measurements, we have suggested that TFE-protein interaction 47 includes a combination of both solvent-mediated effects and direct binding. The ITC results in the present studies ( Figures 8 and supplement 2) show that the heat liberated at each injection is nearly zero and the overall ITC profile does not indicate a significant binding pattern.…”

The role of interfacial viscoelasticity in the stabilization of an electrospun jet

“…In solution #2, the protein's native structure is partially altered due to the good solvating properties of the TFE, and the protein chains are stabilized in a so-called partially-unfolded state, as described elsewhere [29][30][31]. Additionally, the TFE prevents inter-molecular interactions between the partially-unfolded protein coils, preventing the formation of an organized lattice in this solution and resulting in a Newtonian flow behavior.…”

About the albumin structure in solution and related electro-spinnability issues

“…Most prominently, at high TFE concentrations, the interactions of the protein hydrophilic regimes with water molecules as well as the associated hydrophobic interactions within the protein are disrupted by TFE [27,[37][38][39]. The bulk effect causes unfolding of the tertiary structure of the proteins while concurrently strengthening some intra-molecular hydrogen bonds involved with secondary structures, such as˛-helixes.…”