Surfactant protein SP-B induces ordering at the surface of model membrane bilayers
| Autor: | Jeffrey A. Whitsett, John E. Baatz, Barry Elledge |
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| Rok vydání: | 1990 |
| Předmět: |
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2-Dipalmitoylphosphatidylcholine Surface Properties Membrane lipids Proteolipids Lipid Bilayers Molecular Sequence Data Analytical chemistry Fluorescence spectrometry Phospholipid Synthetic membrane Fluorescence Polarization Biochemistry chemistry.chemical_compound Membrane Lipids Animals Amino Acid Sequence Fluorescent Dyes Phosphatidylglycerol Bilayer technology industry and agriculture Membrane Proteins Phosphatidylglycerols Pulmonary Surfactants Membrane chemistry Biophysics lipids (amino acids peptides and proteins) Cattle Fluorescence anisotropy |
| Zdroj: | Biochemistry. 29(28) |
| ISSN: | 0006-2960 |
| Popis: | The effects of bovine pulmonary surfactant-associated protein B (SP-B) on molecular packing of model membrane lipids (7:1 DPPC/DPPG) were studied by fluorescence anisotropy. The bilayer surface was markedly ordered by SP-B below the gel to fluid phase transition temperature (Tc) while it was only slightly ordered above this temperature as indicated by surface-sensitive probes 6-NBD-PC and 6-NBD-PG. The effects of SP-B on fluorescence anisotropy were concentration dependent, reaching maximal activity at 1-2% protein to phospholipid by weight. Anisotropy measurements of interior-selective fluorescent probes (cis-parinaric acid and DPH) imply that addition of SP-B into the phospholipid shifted the Tc of the model membrane but did not alter lipid order at the membrane interior. Since fluorescence anisotropy studies with trans-parinaric acid, an interior-sensitive probe with high affinity for gel-phase lipids, did not detect any changes in lipid packing or Tc, it is likely that SP-B resides primarily in fluid-phase domains. Fluorescence lifetime measurements indicated that two conformers of the NBD-PC probe exist in this DPPC/DPPG model membrane system. Fluorescence intensity measurements generated with NBD-PC and NBD-PG, in conjunction with information from lifetime measurements, support the concept that SP-B increases the distribution of the short-lifetime conformer in the gel phase. In addition, the anisotropy and intensity profiles of NBD-PG in the model membrane indicate that bovine SP-B interacts selectively with phosphatidylglycerol. |
| Databáze: | OpenAIRE |
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