title: Tuning of protein-surfactant interaction to modify the resultant structure.
abstract: Small-angle neutron scattering and dynamic light scattering studies have been carried out to examine the interaction of bovine serum albumin (BSA) protein with different surfactants under varying solution conditions. We show that the interaction of anionic BSA protein (pH7) with surfactant and the resultant structure are strongly modified by the charge head group of the surfactant, ionic strength of the solution, and mixed surfactants. The protein-surfactant interaction is maximum when two components are oppositely charged, followed by components being similarly charged through the site-specific binding, and no interaction in the case of a nonionic surfactant. This interaction of protein with ionic surfactants is characterized by the fractal structure representing a bead-necklace structure of micellelike clusters adsorbed along the unfolded protein chain. The interaction is enhanced with ionic strength only in the case of site-specific binding of an anionic surfactant with an anionic protein, whereas it is almost unchanged for other complexes of cationic and nonionic surfactants with anionic proteins. Interestingly, the interaction of BSA protein with ionic surfactants is significantly suppressed in the presence of nonionic surfactant. These results with mixed surfactants thus can be used to fold back the unfolded protein as well as to prevent surfactant-induced protein unfolding. For different solution conditions, the results are interpreted in terms of a change in fractal dimension, the overall size of the protein-surfactant complex, and the number of micelles attached to the protein. The interplay of electrostatic and hydrophobic interactions is found to govern the resultant structure of complexes.
authors.affiliation: Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
authors.forename: Sumit
authors.initials: S
authors.lastname: Mehan
authors.affiliation: Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
authors.forename: Vinod K
authors.initials: VK
authors.lastname: Aswal
authors.affiliation: Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 PSI Villigen, Switzerland.
authors.forename: Joachim
authors.initials: J
authors.lastname: Kohlbrecher
mesh_terms: D000818:Animals; D002417:Cattle; D000067493:Dynamic Light Scattering; D017709:Fractals; D057927:Hydrophobic and Hydrophilic Interactions; D007477:Ions / Q000737:chemistry; D008823:Micelles; D008956:Models, Chemical; D033363:Neutron Diffraction; D011092:Polyethylene Glycols / Q000737:chemistry / Q000494:pharmacology; D017510:Protein Folding / Q000187:drug effects; D000644:Quaternary Ammonium Compounds / Q000737:chemistry / Q000494:pharmacology; D053838:Scattering, Small Angle; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry / Q000494:pharmacology; D055672:Static Electricity; D013501:Surface-Active Agents / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D007477:Ions; D008823:Micelles; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; C478747:polyoxyethylene-10-dodecyl ether; D012710:Serum Albumin, Bovine; D012967:Sodium Dodecyl Sulfate; D011092:Polyethylene Glycols; C022806:dodecyltrimethylammonium