A small-angle X-ray scattering study of the structure of lysozyme–sodium dodecyl sulfate complexes

• Published in: Journal of colloid and interface science Vol. 328; no. 1; pp. 67 - 72
• Main Authors: Narayanan, Janaky, Abdul Rasheed, A.S., Bellare, Jayesh R.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.12.2008; Elsevier
• Subjects: Animals; Chemistry; Chickens; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Lysozyme; Micelles; Micelles. Thin films; Muramidase - chemistry; Protein–surfactant complex; Scattering, Small Angle; Small-angle X-ray scattering; Sodium dodecyl sulfate; Sodium Dodecyl Sulfate - chemistry; Surface physical chemistry; Surface-Active Agents - chemistry; X-Ray Diffraction; Sodium dodecyl sulfate; Protein–surfactant complex; Micelles; Lysozyme; Small-angle X-ray scattering; Sodium complex; Growth; Micelle; Surfactant; Small angle X ray scattering; Paraffin; Ionic surfactant; Mean spherical approximation; Sodium sulfate; Electron density; Structure; Complexation; Enzyme; Protein; Lauryl sulfate; Glycosylases; Anionic surfactant; Protein-surfactant complex; Polypeptide; Glycosidases; Hydrolases; Models
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2008.09.012

The structure of lysozyme–sodium dodecyl sulfate (SDS) complexes in solution is studied using small-angle X-ray scattering (SAXS). The SAXS data cannot be explained by the necklace and bead model for unfolded polypeptide chain interspersed with surfactant micelles. For the protein and surfactant concentrations used in the study, there is only marginal growth of SDS micelles as they complex with the protein. Being a small and rather rigid protein, lysozyme can penetrate the micellar core which is occupied by flexible and disordered paraffin chains and also the shell occupied by the hydrated head groups. A partially embedded swollen micellar model seems appropriate and describes well the scattering data. The SAXS intensity profiles are analyzed by considering the change in the electron scattering length density of the micellar core and shell due to complexation with protein and treating the intermicellar interaction using rescaled mean spherical approximation (RMSA) for charged spheres. Lysozyme–SDS complex with protein in native and slightly unfolded states. Protein lying close to the core–shell boundary modifies the electron densities of the core and shell.