Ultraviolet–circular dichroism spectroscopy and potentiometric study of the interaction between human serum albumin and sodium perfluorooctanoate

Abstract

The interaction of a fluorinated surfactant, sodium perfluorooctanoate, with human serum albumin (HSA) has been investigated by a combination of ultraviolet-circular dichroism (UV-CD) spectroscopy and potentiometry (by a home-built ion-selective electrode) techniques to detect and characterize the conformational transitions of HSA. By using difference spectroscopy, the transition was followed as a function of temperature, and the data were analyzed to obtain the parameters characterizing the thermodynamics of unfolding. The results indicate that the presence of surfactant drastically changes the melting unfolding, acting as a structure stabilizer and delaying the unfolding process. Potentiometric measurements were used to determine the binding isotherms and binding capacity for this system. The isotherm shows a high affinity of surfactant molecules for HSA. The average number of surfactant molecules absorbed per protein molecule (at 28 mM of surfactant concentration) was found to be approximately 900, about 6 g of surfactant per gram of protein. The shape of the binding capacity curve and the relation between binding capacity and extend of cooperativity were examined. From these analysis, the values of g (number of ligand-binding sites), KH (Hill binding constant), and nH (Hill coefficient) were determined.

Protein–surfactant interaction: Differences between fluorinated and hydrogenated surfactants

“…In gen- eral, fluorinated surfactants have stronger hydrophobicity than hydrogenated ones with similar hydrophobic chain length. In the case that the fluorinated and hydrogenated surfactants have similar hydrophobic chain length, it could be expected that hydrophobic interactions became much stronger in systems of fluorinated surfactants and proteins due to the higher hydrophobicity of fluorine atoms [7][8][9]. In this work we compared the fluorinated and hydrogenated surfactants with similar cmc values, it shows that the discrepancy of the two kinds of surfactants is related to the properties of proteins and anionic surfactants.…”

“…Previous works have focused on conventional surfactants whose hydrophobe is usually a hydrocarbon group, so-called hydrogenated surfactants or hydrocarbon surfactants [1]. However, there is one kind of special surfactants, fluorinated surfactants or fluorocarbon surfactants, whose interaction with proteins remained rarely studied [2][3][4][5][6][7][8][9][10]. In fluorinated surfactants, all or most hydrogen atoms in the hydrophobe are replaced by fluorine atoms.…”

The Influence of Sodium Perfluorooctanoate on the Conformational Transitions of Human Immunoglobulin

“…Similar curves were found in previous works for insulin-nalkylsulfates 17 and for HSA-SPFO interactions. 4 …”

Influence of the Ring Size on the Binding Ability of FTO Investigated by Fluorescence Spectroscopy

“…The nature and magnitude of drug-protein interaction significantly influences the biological activity of the drug. Several analytical methods have been used to qualitatively and quantitatively study the binding of ligands to protein [7][8][9][10][11]. Fluorescence techniques are great aids in the study of interactions between drugs and proteins because of the high sensitivity, Wu He and Zhigang Li contributed equally to this work.…”