title: Synchrotron X-ray study of lung surfactant-specific protein SP-B in lipid monolayers.
abstract: This work reports the first x-ray scattering measurements 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, in agreement with fluorescence microscopy studies. X-ray reflectivity shows that the peptide is oriented in the lipid monolayer at an angle of approximately 56 degrees relative to the interface normal, with one end protruding past the hydrophilic region into the fluid subphase and the other end embedded in the hydrophobic region of the monolayer. The quantitative insights afforded by this study lead to a better understanding of the lipid/protein interactions found in lung surfactant systems.
authors: Department of Chemistry and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, USA. kayeelee@uchicago.edu
authors: K Y
authors: KY
authors: Lee
authors: J
authors: J
authors: Majewski
authors: T L
authors: TL
authors: Kuhl
authors: P B
authors: PB
authors: Howes
authors: K
authors: K
authors: Kjaer
authors: M M
authors: MM
authors: Lipp
authors: A J
authors: AJ
authors: Waring
authors: J A
authors: JA
authors: Zasadzinski
authors: G S
authors: GS
authors: Smith
mesh_terms: D000595:Amino Acid Sequence; D050356:Lipid Metabolism; D008567:Membranes, Artificial; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D019308:Palmitic Acid / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011510:Proteolipids / Q000737:chemistry* / Q000378:metabolism*; D011663:Pulmonary Surfactants / Q000737:chemistry* / Q000378:metabolism*; D012965:Sodium Chloride / Q000378:metabolism; D017356:Synchrotrons; D013696:Temperature; D014867:Water / Q000378:metabolism; D014961:X-Ray Diffraction / Q000295:instrumentation* / Q000379:methods*
chemical_list: D008567:Membranes, Artificial; D011510:Proteolipids; D011663:Pulmonary Surfactants; D014867:Water; D019308:Palmitic Acid; D012965:Sodium Chloride