Interaction of gramicidin with DPPC/DODAB bilayer fragments.
| Autor: | Carvalho CA; Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, CP 26077, CEP 05513-970, São Paulo, SP, Brazil., Olivares-Ortega C, Soto-Arriaza MA, Carmona-Ribeiro AM |
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| Jazyk: | angličtina |
| Zdroj: | Biochimica et biophysica acta [Biochim Biophys Acta] 2012 Dec; Vol. 1818 (12), pp. 3064-71. Date of Electronic Publication: 2012 Aug 18. |
| DOI: | 10.1016/j.bbamem.2012.08.008 |
| Abstrakt: | The interaction between the antimicrobial peptide gramicidin (Gr) and dipalmitoylphosphatidylcholine (DPPC)/dioctadecyldimethylammonium bromide (DODAB) 1:1 large unilamellar vesicles (LVs) or bilayer fragments (BFs) was evaluated by means of several techniques. The major methods were: 1) Gr intrinsic fluorescence and circular dichroism (CD) spectroscopy; 2) dynamic light scattering for sizing and zeta-potential analysis; 3) determination of the bilayer phase transition from extrinsic fluorescence of bilayer probes; 4) pictures of the dispersions for evaluation of coloidal stability over a range of time and NaCl concentration. For Gr in LVs, the Gr dimeric channel conformation is suggested from: 1) CD and intrinsic fluorescence spectra similar to those in trifluoroethanol (TFE); 2) KCl or glucose permeation through the LVs/Gr bilayer. For Gr in BFs, the intertwined dimeric, non-channel Gr conformation is evidenced by CD and intrinsic fluorescence spectra similar to those in ethanol. Both LVs and BFs shield Gr tryptophans against quenching by acrylamide but the Stern-Volmer quenching constant was slightly higher for Gr in BFs confirming that the peptide is more exposed to the water phase in BFs than in LVs. The DPPC/DODAB/Gr supramolecular assemblies may predict the behavior of other antimicrobial peptides in assemblies with lipids. (Copyright © 2012 Elsevier B.V. All rights reserved.) |
| Databáze: | MEDLINE |
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