Influence of Fluoro, Chloro and Alkyl Alcohols on the Folding Pathway of Human Serum Albumin

Publisher Website
Google Scholar
Abstract
Urea-induced equilibrium unfolding of human serum albumin (HSA) when studied by mean residue ellipticity at 222 nm (MRE222) or intrinsic fluorescence measurements showed a two-step, three-state transition with a stable intermediate around 4.6–5.2 M urea. The presence of 2,2,2-trifluoroethanol (TFE) resulted in a single-step, two-state transition with a significant shift towards higher urea concentration, suggesting the stabilizing effect of TFE. The free energy of stabilization (ΔΔGDH2O) in the presence of 3.0 M TFE was determined to be 2.68 and 2.72 kcal/mol by MRE222 and fluorescence measurements, respectively. The stabilizing potential of other alcohols on the refolding behavior of HSA at 5.0 M urea (where the intermediate exists) as studied by MRE222 and intrinsic fluorescence measurements showed the following order: 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) > TFE > 2-chloroethanol > tert-butanol > iso-propanol > ethanol > methanol. Further, the extent of refolding at the highest concentration of alcohol was similar in all cases. The stabilizing effect of TFE on guanidine hydrochloride (GdnHCl)–induced unfolding of HSA was nearly equal to that found for urea denaturation, as reflected in the ΔΔGDH2O value (2.38 kcal/mol). Taken together, these results suggest that the stabilizing effect of TFE and other alcohols on urea/GdnHCl-induced unfolding of HSA is higher for alcohols that contain bulky groups or fluorine atoms.

This publication has 64 references indexed in Scilit: