Structure, Orientation and Stability of Lysozyme Confined in layered Materials

Abstract : The confinement of lysozyme in 3 layered materials based on montmorillonite and lamellar double hydroxide exhibiting different surface charges was studied. The protein structure and orientation in these materials were determined by X-Ray diffraction, time resolved fluorescence and fluorescence anisotropy. For both Montmorillonite exchanged with sodium and modified with non-ionic surfactant (tri-ethylene glycol mono n-decyl ether), the lysozyme was found to be located in the interlayer space with "end-on" and "side-on" orientation, respectively. Conversely no lysozyme intercalation was observed with lamellar double hydroxide modified with anionic surfactant (sodium octylsulfate), since protein was adsorbed on the surface of the particles. Fourier transformed infra-red spectroscopy analysis shows that lysozyme confinement in the interlayer space preserves its structure after dehydration, whereas some structural changes were observed for lysozyme adsorbed on the particle surface.