Hydrophobic surfactant proteins induce a phosphatidylethanolamine to form cubic phases

Mariya Chavarha, Hamed Khoojlnlan, Leonard E. Schulwitz, Samares C. Biswas, Shankar B. Rananavare, Stephen B. Hall

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


The hydrophobic surfactant proteins SP-B and SP-C promote rapid adsorption of pulmonary surfactant to an air/ water interface. Previous evidence suggests that they achieve this effect by facilitating the formation of a rate-limiting negatively curved stalk between the vesicular bilayer and the interface. To determine whether the proteins can alter the curvature of lipid leaflets, we used x-ray diffraction to investigate how the physiological mixture of these proteins affects structures formed by 1-palmitoyl-2-oleoyl phosphatidylethanolamine, which by itself undergoes the lamellar-to-inverse hexagonal phase transition at 71°C. In amounts as low as 0.03% (w:w) and at temperatures as low as 57°C, the proteins induce formation of bicontinuous inverse cubic phases. The proteins produce a dose-related shift of diffracted intensity to the cubic phases, with minimal evidence of other structures above 0.1% and 62°C, but no change in the lattice-constants of the lamellar or cubic phases. The induction of the bicontinuous cubic phases, in which the individual lipid leaflets have the same saddle-shaped curvature as the hypothetical stalk-intermediate, supports the proposed model of how the surfactant proteins promote adsorption.

Original languageEnglish (US)
Pages (from-to)1549-1557
Number of pages9
JournalBiophysical Journal
Issue number8
StatePublished - Apr 21 2010

ASJC Scopus subject areas

  • Biophysics


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