The incorporation of lung surfactant specific protein SP-B into lipid monolayers at the air-fluid interface: A grazing incidence x-ray diffraction study

Grazing incidence x-ray diffraction (GIXD) measurements were performed to determine the effects of SP-B(1-25), the N-terminus peptide of lung surfactant specific protein SP-B, on the structure of palmitic acid (PA) monolayers. In-plane diffraction shows that the peptide fluidizes a portion of the monolayer, but does not affect the packing of the residual ordered phase. This implies that the peptide resides in the disordered phase, and that the ordered phase is essentially pure lipid. The quantitative insights afforded by this study lead to a better understanding of the lipid/protein interactions found in lung surfactant systems.