Raman spectroscopy of synthetic antimicrobial frog peptides magainin 2a and PGLa
| Autor: | Ruth Starman, Troy Beeler, Michael Zasloff, Kenneth Gable, David Covell, Robert W. Williams, Kenneth M. P. Taylor |
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| Rok vydání: | 1990 |
| Předmět: |
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2-Dipalmitoylphosphatidylcholine Protein Conformation Molecular Sequence Data Peptide Xenopus Proteins Magainins Spectrum Analysis Raman Biochemistry chemistry.chemical_compound Xenopus laevis Phosphatidylcholine Animals Amino Acid Sequence Protein secondary structure chemistry.chemical_classification Liposome Bilayer Magainin Phosphatidylglycerols Amides Melitten Membrane Spectrometry Fluorescence chemistry Liposomes Peptides Alpha helix Antimicrobial Cationic Peptides |
| Zdroj: | Biochemistry. 29(18) |
| ISSN: | 0006-2960 |
| Popis: | Magainin and PGLa are 23- and 21-residue peptides isolated from the skin of the African clawed frog Xenopus lueuis. They protect the frog from infection and exhibit a broad-spectrum antimicrobial activity in vitro. The mechanism of this activity involves the interaction of magainin with microbial membranes. We have measured the secondary structure and membrane-perturbing ability of these peptides to obtain information about this mechanism. Our results show that mgn2a forms a helix with an average length of less than 20 A upon binding to liposomes. At high concentrations (50 mg/mL) mgn2a spontaneously solubilizes phosphatidylcholine liposomes at temperatures above the gel-liquid-crystalline phase transition. Mgn2a appears to bind to the surface of liposomes made of negatively charged lipids without spontaneously penetrating the bilayer. Finally, mgn2a and PGLa interact together with liposomes in a synergistic way that enhances the helix content of one or both of the peptides and allows the peptides to more easily penetrate the bilayer. PGLa mixed with a small nonperturbing amount of magainin 2 amide is 25-43 times as potent as PGLa alone at inducing the release of carboxyfluorescein from liposomes. The results suggest that the mechanism of antimicrobial activity does not involve a channel formed by transmembrane helical peptides. |
| Databáze: | OpenAIRE |
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