Kinetics of phospholipid membrane fusion induced by surfactant apoproteins A and B

Francis R Poulain, Shlomo Nir, Samuel Hawgood

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


Surfactant apoproteins A (SP-A) and B (SP-B) interact with the lipids of surfactant and such protein-lipid interactions may be of importance in several of the steps in the surfactant cycle. We analyzed the kinetics of fusion of dipalmitoylphosphatidylcholine-phosphatidylglycerol (DPPC:PG; 7:3, w/w) phospholipid vesicles induced by SP-B alone, in the presence of 5 mM calcium, and in the presence of calcium and SP-A. Membrane fusion was measured by the method of resonance energy transfer between non-exchangeable fluorophores incorporated in the membrane. Data were analyzed using a mass action kinetic model for membrane fusion between phospholipid vesicles. We found a SP-B dose-dependent increase in lipid mixing within a range of phospholipid concentration of 5 to 100 μM. Calcium caused a small additive increase in lipid mixing, but calcium and SP-A combined markedly increased lipid mixing induced by SP-B. Both aggregation and fusion rate constants increased with an increase in the SP-B/lipid ratio. In the presence of calcium and SP-A, the number of vesicles per fusion product markedly increased, as did the aggregation rate constants, whereas the fusion rate constants remained essentially unchanged.

Original languageEnglish (US)
Pages (from-to)169-175
Number of pages7
JournalBiochimica et Biophysica Acta - Biomembranes
Issue number2
StatePublished - Jan 31 1996
Externally publishedYes


  • Kinetics
  • Membrane fusion
  • Myelin
  • Surfactant
  • Surfactant apoprotein
  • Tubular myelin

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Biophysics


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