The LγPhase of Pulmonary Surfactant

Kamlesh Kumar, Mariya Chavarha, Ryan W. Loney, Thomas M. Weiss, Shankar Balasaheb Rananavare, Stephen (Steve) Hall

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

To determine how different components affect the structure of pulmonary surfactant, we measured X-ray scattering by samples derived from calf surfactant. The surfactant phospholipids demonstrated the essential characteristics of the Lγ phase: a unit cell with a lattice constant appropriate for two bilayers; crystalline chains detected by wide angle X-ray scattering (WAXS). The electron density profile, obtained from scattering by oriented films at different relative humidities (70-97%), showed that the two bilayers, arranged as mirror images, each contain two distinct leaflets with different thicknesses and profiles. The detailed structures suggest one ordered leaflet that would contain crystalline chains, and one disordered monolayer likely to contain the anionic compounds, which constitute ~10% of the surfactant phospholipids. The spacing and temperature-dependence detected by WAXS fit with an ordered leaflet composed of dipalmitoyl phosphatidylcholine. Physiological levels of cholesterol had no effect on this structure. Removing the anionic phospholipids prevented formation of the Lγ phase. The cationic surfactant proteins inhibited Lγ structures, but at levels unlikely related to charge. Because the Lγ phase, if arranged properly, could produce a self-assembled ordered interfacial monolayer, the structure could have important functional consequences. Physiological levels of the proteins, however, inhibit formation of the Lγ structures at high relative humidities, making their physiological significance uncertain.

Original languageEnglish (US)
JournalUnknown Journal
DOIs
StateAccepted/In press - Feb 9 2018

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Keywords

  • asymmetric bilayer
  • lipid polymorphism
  • lung
  • surface tension
  • X-ray diffraction

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

Cite this

Kumar, K., Chavarha, M., Loney, R. W., Weiss, T. M., Rananavare, S. B., & Hall, S. S. (Accepted/In press). The LγPhase of Pulmonary Surfactant. Unknown Journal. https://doi.org/10.1021/acs.langmuir.8b00460