On the Effect of pH, Temperature, and Surfactant Structure on Bovine Serum Albumin–Cationic/Anionic/Nonionic Surfactants Interactions in Cacodylate Buffer–Fluorescence Quenching Studies Supported by UV Spectrophotometry and CD Spectroscopy

Abstract

Due to the fact that surfactant molecules are known to alter the structure (and consequently the function) of a protein, protein–surfactant interactions are very important in the biological, pharmaceutical, and cosmetic industries. Although there are numerous studies on the interactions of albumins with surfactants, the investigations are often performed at fixed environmental conditions and limited to separate surface-active agents and consequently do not present an appropriate comparison between their different types and structures. In the present paper, the interactions between selected cationic, anionic, and nonionic surfactants, namely hexadecylpyridinium chloride (CPC), hexadecyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), polyethylene glycol sorbitan monolaurate, monopalmitate, and monooleate (TWEEN 20, TWEEN 40, and TWEEN 80, respectively) with bovine serum albumin (BSA) were studied qualitatively and quantitatively in an aqueous solution (10 mM cacodylate buffer; pH 5.0 and 7.0) by steady-state fluorescence spectroscopy supported by UV spectrophotometry and CD spectroscopy. Since in the case of all studied systems, the fluorescence intensity of BSA decreased regularly and significantly under the action of the surfactants added, the fluorescence quenching mechanism was analyzed thoroughly with the use of the Stern–Volmer equation (and its modification) and attributed to the formation of BSA–surfactant complexes. The binding efficiency and mode of interactions were evaluated among others by the determination, comparison, and discussion of the values of binding (association) constants of the newly formed complexes and the corresponding thermodynamic parameters (ΔG, ΔH, ΔS). Furthermore, the influence of the structure of the chosen surfactants (charge of hydrophilic head and length of hydrophobic chain) as well as different environmental conditions (pH, temperature) on the binding mode and the strength of the interaction has been investigated and elucidated.

A Novel 3D Printing Particulate Manufacturing Technology for Encapsulation of Protein Therapeutics: Sprayed Multi Adsorbed-Droplet Reposing Technology (SMART)

“…The biological activity of the proteins is highly impacted by their secondary structure [ 56 , 57 ]. Some operational conditions such as a harsh temperature or a pH change or the presence of specific chemicals may cause conformational changes as well as protein unfolding and, consequently, the loss of activity [ 58 , 59 , 60 ]. Several studies reported trypsin conformational changes in the presence of environmental conditions such as the presence of salts, various solvents, and temperature [ 61 , 62 , 63 , 64 , 65 ].…”

Evolution of the structure and interaction in the surfactant-dependent heat-induced gelation of protein

“…15,16,18 A strong dependence of the interaction between the two components on temperature has also been reported, where binding energy, critical aggregation concentration and other thermodynamical parameters have been shown to be influenced by temperature variation. 20–22 However, in most cases, the temperature range studied remains close to room temperature, where neither the protein, nor the surfactant, nor their complexes undergo significant macroscopic changes. 2,16,20–22 Temperature is a critical parameter for influencing protein–surfactant interactions as it is known to affect protein conformation and drives morphological transitions in surfactants.…”

“…20–22 However, in most cases, the temperature range studied remains close to room temperature, where neither the protein, nor the surfactant, nor their complexes undergo significant macroscopic changes. 2,16,20–22 Temperature is a critical parameter for influencing protein–surfactant interactions as it is known to affect protein conformation and drives morphological transitions in surfactants. 23–29 When subjected to high temperatures, proteins undergo unfolding.…”