A study of the structure of polymyxin B-dipalmitoylphosphatidylglycerol complexes by vibrational spectroscopy
| Autor: | Marie Pigeon, Yves Babin, Jacynthe D'Amour, Michel Pézolet |
|---|---|
| Rok vydání: | 1987 |
| Předmět: |
Phase transition
Spectrophotometry Infrared medicine.drug_class Polymyxin Lipid Bilayers Biophysics Analytical chemistry Phospholipid Molecular Conformation Infrared spectroscopy Spectrum Analysis Raman Biochemistry chemistry.chemical_compound symbols.namesake X-Ray Diffraction medicine Molecule Polymyxins Polymyxin B Bilayer Temperature Phosphatidylglycerols Cell Biology Hydrogen-Ion Concentration Crystallography chemistry symbols lipids (amino acids peptides and proteins) Raman spectroscopy medicine.drug |
| Zdroj: | Biochimica et biophysica acta. 903(1) |
| ISSN: | 0006-3002 |
| Popis: | The effect of the antibiotic polymyxin B on dipalmitoylphosphatidylglycerol (DPPG) bilayers has been studied by Raman and infrared spectroscopies and small-angle X-ray diffraction. Each polymyxin B molecule binds five DPPG molecules at physiological pH and induces a macroscopic phase separation of the complex rather than a lateral phase separation. Below the phase transition of DPPG/polymyxin B bilayers, the results obtained show that the intermolecular vibrational coupling is high and suggest that the acyl chains of the bound lipid are interdigitated and that the hydrophobic tail of the antibiotic does not penetrate this tight assembly. On the other hand, the phase transition of DPPG is shifted down from 41 degrees C to 37 degrees C in the complexes and remains highly cooperative. Above the phase transition of the complexes, the conformation of the acyl chains of DPPG is slightly more disordered as a result of the penetration of the polymyxin chain, but the structure of the glycerol backbone of the lipid does not seem to be affected. However, the rotational rate of the lipid appears to be restricted by the peptide. |
| Databáze: | OpenAIRE |
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