Expression and Characterization of Recombinant Lung Surfactant Protein-B (rSP-B)

Lung surfactant proteins play a crucial role in breathing and also help defend the lungs from pathogens. SP-B is essential to life. The atomic resolution structure of SP-B has not yet been determined; hence, the molecular mechanism for its activity is not well understood. Our lab has managed to express rSP-B in bacteria, purify and refold it into detergent and lipid. Far UV circular dichroism of rSP-B indicates native-like secondary structure that is stable over a range of temperatures and in different membrane-mimetic compositions. Dynamic light scattering indicates a hydrodynamic radius of protein-detergent complexes of ~300 nm, which is of interest in determining the functional oligomeric form of SP-B. Consistent results are obtained with nanoparticle tracking analysis. Pressure/area isotherms provide an in vitro measure of the interfacial activity of rSP-B that resembles results for native and clinical surfactants at physiological SP-B concentrations.