Protein Detergent Interactions
Synthetic surfactants are found in almost every sector of modern industry and in daily human life. Protein-surfactant interactions occur in many applications within the food, laundry and pharmaceutical sector. Surfactants inhibit protein aggregation, essential for long-term storage of pharmaceutical products. Surfactant-induced unfolding/denaturation of proteins improves surface properties and promotes enzymatic degradation in laundry detergents. In the food industry surfactants act as emulsifying-, foaming-, antioxidant agents, stabilizers and anti-adhesives.
We have previously shown that unfolding of globular proteins in anionic and cationic detergents is substantially different from unfolding in chemical denaturants due to the changing structures and complex binding properties of detergents, but can be subjected to protein engineering analysis (1-3). In addition, refolding of proteins from the SDS-denatured state by addition of cyclodextrins can also provide a useful short-cut to determine protein folding rates in water (4).
More recently, we have demonstrated a remarkable ability of different detergents at the monomer level in activating and inhibiting lipase activity (21), an activity which traditionally has been regarded as requiring an aggregated detergent rather than monomer. We have systematically analyzed the unfolding of model proteins from different structural classes to extract more general principles for detergent-protein interactions (5-10). Together with Professor Jan Skov Pedersen we have made significant advances using Small Angle X-ray Scattering, and have developed a model (see below, taken from (6)) in which several proteins "contribute" detergent micelles to come together as a shared micelle. Our work has been reviewed recently (11).
Protein detergent interactions
- 1. Otzen, D. E. (2002) Protein unfolding in detergents: Effect of micelle structure, ionic strength, pH, and temperature, Biophys. J. 83, 2219-2230.
- 2. Otzen, D. E., and Oliveberg, M. (2002) Burst-phase expansion of native protein prior to global unfolding in SDS, Journal of Molecular Biology 315, 1231-1240.
- 3. Otzen, D. E., Christiansen, L., and Schülein, M. (1999) A comparative study of the unfolding of the endoglucanase Cel45 from Humicola insolens in denaturant and surfactant, Prot. Sci. 8, 1878-1887.
- 4. Otzen, D. E., and Oliveberg, M. (2001) A simple way to measure protein refolding rates in water, Journal of Molecular Biology 313, 479-483.
- 5. Andersen, K., Westh, P., and Otzen, D. E. (2008) A global study of myoglobin-surfactant interactions, Langmuir 15, 399-407.
- 6. Andersen, K. K., Oliveira, C. L. P., Larsen, K. L., Poulsen, F. M., Callisen, T. H., Westh, P., Pedersen, J. S., and Otzen, D. E. (2009) The role of decorated SDS micelles in sub-cmc protein denaturation and association, Journal of Molecular Biology 391, 207-226.
- 7. Andersen, K. K., and Otzen, D. E. (2009) How chain length and charge affect surfactant denaturation of ACBP, J. Phys. Chem. B 113, 13942-13952.
- 8. Nielsen, M. M., Andersen, K. K., Westh, P., and Otzen, D. E. (2007) Unfolding of b-sheet proteins in SDS, Biophys. J. 92, 3674-3685.
- 9. Otzen, D. E., Sehgal, P., and Westh, P. (2009) a-lactalbumin is unfolded by all classes of detergents but with different mechanisms, J. Coll. Int. Sci. 329, 273-283.
- 10. Hansted, J. G., Wejse, P. L., Bertelsen, H., and Otzen, D. E. (2011) Effect of protein-surfactant interactions on aggregation of ?-lactoglobulin, Biochim. Biophys. Acta 1814, 713-723.
- 11. Otzen, D. E. (2011) Protein-surfactant interactions: a tale of many states, Biochim. Biophys. Acta 1814, 562-591.