Association and Interactions in Protein-Surfactant Systems

Sammanfattning: Aggregation in protein-surfactant systems have been studied with the ambition of reaching a deeper understanding of the balance of the interaction forces involved. A pure system with maximized electrostatic interactions has been used. The approach has been to use a step-wise sample preparation where initially a stoichiometric protein-surfactant salt is precipitated and freeze-dried. Secondly, the solubilization of the protein-surfactant salts has been studied both in excess of the parent surfactant and by addition of another surfactant. The mechanisms for solubilization in the two cases are not the same but dependent on the surfactant and surfactant-surfactant aggregation behavior, respectively. The solubilization is studied by Nuclear Magnetic Resonance (NMR) diffusometry, Raman spectroscopy and UV absorption spectroscopy. Further, the gel formed in the lysozyme-alkylsulfate-water systems is analyzed in terms of both the question of its thermodynamic status and its structure. The latter is approached by Small Angle Neutron Scattering (SANS) and Transmission Electron Microscopy (TEM). Finally, the more complex system of the surfactant aggregation with the photosynthetic light-harvesting antenna (LH2) is studied in the light of the surfactant self-aggregation pattern.