Document Detail

Interactions of pulmonary surfactant protein A with phospholipid monolayers change with pH.
MedLine Citation:
PMID:  10465757     Owner:  NLM     Status:  MEDLINE    
The interaction of pulmonary surfactant protein A (SP-A) labeled with Texas Red (TR-SP-A) with monolayers containing zwitterionic and acidic phospholipids has been studied at pH 7.4 and 4.5 using epifluorescence microscopy. At pH 7.4, TR-SP-A expanded the pi-A isotherms of film of dipalmitoylphosphatidylcholine (DPPC). It interacted at high concentration at the edges of condensed-expanded phase domains, and distributed evenly at lower concentration into the fluid phase with increasing pressure. At pH 4.5, TR-SP-A expanded DPPC monolayers to a slightly lower extent than at pH 7.4. It interacted primarily at the phase boundaries but it did not distribute into the fluid phase with increasing pressure. Films of DPPC/dipalmitoylphosphatidylglycerol (DPPG) 7:3 mol/mol were somewhat expanded by TR-SP-A at pH 7.4. The protein was distributed in aggregates only at the condensed-expanded phase boundaries at all surface pressures. At pH 4.5 TR-SP-A caused no expansion of the pi-A isotherm of DPPC/DPPG, but its fluorescence was relatively homogeneously distributed throughout the expanded phase at all pressures studied. These observations can be explained by a combination of factors including the preference for SP-A aggregates to enter monolayers at packing dislocations and their disaggregation in the presence of lipid under increasing pressure, together with the influence of pH on the aggregation state of SP-A and the interaction of SP-A with zwitterionic and acidic lipid.
M L Ruano; K Nag; C Casals; J Pérez-Gil; K M Keough
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biophysical journal     Volume:  77     ISSN:  0006-3495     ISO Abbreviation:  Biophys. J.     Publication Date:  1999 Sep 
Date Detail:
Created Date:  1999-10-08     Completed Date:  1999-10-08     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0370626     Medline TA:  Biophys J     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1469-76     Citation Subset:  IM    
Departamento de Bioquímica, Facultad de Biología, Universidad Complutense, 28040 Madrid, Spain.
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MeSH Terms
1,2-Dipalmitoylphosphatidylcholine / chemistry*
Bronchoalveolar Lavage Fluid / chemistry
Fluorescent Dyes
Hydrogen-Ion Concentration*
Liposomes / chemistry*
Microscopy, Fluorescence / methods
Phosphatidylglycerols / chemistry*
Proteolipids / chemistry*,  metabolism*
Pulmonary Surfactant-Associated Protein A
Pulmonary Surfactant-Associated Proteins
Pulmonary Surfactants / chemistry*,  metabolism*
Reg. No./Substance:
0/Fluorescent Dyes; 0/Liposomes; 0/Phosphatidylglycerols; 0/Proteolipids; 0/Pulmonary Surfactant-Associated Protein A; 0/Pulmonary Surfactant-Associated Proteins; 0/Pulmonary Surfactants; 0/Xanthenes; 2644-64-6/1,2-Dipalmitoylphosphatidylcholine; 4537-77-3/1,2-dipalmitoylphosphatidylglycerol; 82354-19-6/Texas red

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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