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Interactions of pulmonary surfactant protein A with phospholipid monolayers change with pH.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Ruano, M. Lobo Nag, Kamalaksha Casals, Cristina Pérez-Gil, Jesús Keough, Kevin M. W. |
| Copyright Year | 1999 |
| Abstract | 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. |
| File Format | PDF HTM / HTML |
| DOI | 10.1016/S0006-3495(99)76994-8 |
| Alternate Webpage(s) | http://webs.ucm.es/info/respira/resources/PDF/041.pdf |
| PubMed reference number | 10465757 |
| Alternate Webpage(s) | https://doi.org/10.1016/S0006-3495%2899%2976994-8 |
| Journal | Medline |
| Volume Number | 77 |
| Issue Number | 3 |
| Journal | Biophysical journal |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |