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Please use this identifier to cite or link to this item: http://repositorio.ufla.br/jspui/handle/1/11924

Title: Laurdan spectrum decomposition as a tool for the analysis of surface bilayer structure and polarity: a study with DMPG, peptides and cholesterol
???metadata.dc.creator???: Lúcio, Aline Duarte
Vequi-Suplicy, Cíntia Cristina de
Fernandez, Roberto Morato
Lamy, Maria Teresa Moura
Keywords: Análise espectral – Instrumentos
Laurdan – Fluorescência
Spectrum analysis – Instruments
Laurdan – Fluorescence
Publisher: Springer
Issue Date: 17-Nov-2009
Citation: LUCIO, A. D. et al. Laurdan spectrum decomposition as a tool for the analysis of surface bilayer structure and polarity: a study with DMPG, peptides and cholesterol. Journal of Fluorescence, Maryland, v. 20, n. 2, p. 473-482, Mar. 2010.
Abstract: The highly hydrophobic fluorophore Laurdan (6-dodecanoyl-2-(dimethylaminonaphthalene)) has been widely used as a fluorescent probe to monitor lipid membranes. Actually, it monitors the structure and polarity of the bilayer surface, where its fluorescent moiety is supposed to reside. The present paper discusses the high sensitivity of Laurdan fluorescence through the decomposition of its emission spectrum into two Gaussian bands, which correspond to emissions from two different excited states, one more solvent relaxed than the other. It will be shown that the analysis of the area fraction of each band is more sensitive to bilayer structural changes than the largely used parameter called Generalized Polarization, possibly because the latter does not completely separate the fluorescence emission from the two different excited states of Laurdan. Moreover, it will be shown that this decomposition should be done with the spectrum as a function of energy, and not wavelength. Due to the presence of the two emission bands in Laurdan spectrum, fluorescence anisotropy should be measured around 480 nm, to be able to monitor the fluorescence emission from one excited state only, the solvent relaxed state. Laurdan will be used to monitor the complex structure of the anionic phospholipid DMPG (dimyristoyl phosphatidylglycerol) at different ionic strengths, and the alterations caused on gel and fluid membranes due to the interaction of cationic peptides and cholesterol. Analyzing both the emission spectrum decomposition and anisotropy it was possible to distinguish between effects on the packing and on the hydration of the lipid membrane surface. It could be clearly detected that a more potent analog of the melanotropic hormone α-MSH (Ac-Ser1-Tyr2-Ser3-Met4-Glu5-His6-Phe7-Arg8-Trp9-Gly10-Lys11-Pro12-Val13-NH2) was more effective in rigidifying the bilayer surface of fluid membranes than the hormone, though the hormone significantly decreases the bilayer surface hydration.
URI: http://link.springer.com/article/10.1007/s10895-009-0569-5
???metadata.dc.language???: en_US
Appears in Collections:DEX - Artigos publicados em periódicos
DFI - Artigos publicados em periódicos

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