Solvatochromic Modeling of Laurdan for Multiple Polarity Analysis of Dihydrosphingomyelin Bilayer

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Watanabe N, Goto Y, Suga K, Nyholm TKM, Slotte JP, Umakoshi H
Publisher: Cell Press
Publication year: 2019
Journal: Biophysical Journal
Journal acronym: Biophys J
Volume number: 116
Issue number: 5
Start page: 874
End page: 883
ISSN: 1542-0086


Abstract

The hydration properties of the interface between lipid bilayers
and bulk water are important for determining membrane characteristics.
Here, the emission properties of a solvent-sensitive fluorescence probe,
6-lauroyl-2-dimethylamino naphthalene (Laurdan), were evaluated in
lipid bilayer systems composed of the sphingolipids D-erythro-N-palmitoyl-sphingosylphosphorylcholine (PSM) and D-erythro-N-palmitoyl-dihydrosphingomyelin (DHPSM). The glycerophospholipids 1-palmitoyl-2-palmitoyl-sn-glycero-3-phosphocholine and 1-oleoyl-2-oleoyl-sn-glycero-3-phosphocholine were used as controls. The fluorescence properties of Laurdan in sphingolipid bilayers indicated multiple excited states according to the results obtained from the emission spectra, fluorescence anisotropy,
and the center-of-mass spectra during the decay time. Deconvolution of
the Laurdan emission spectra into four components based on the solvent
model enabled us to identify the varieties of hydration and the
configurational states derived from intermolecular hydrogen bonding in
sphingolipids. Sphingolipids showed specific, interfacial hydration
properties stemming from their intra- and intermolecular hydrogen bonds. Particularly, the Laurdan in DHPSM revealed more hydrated properties compared to PSM, even though DHPSM has a higher Tm
than PSM. Because DHPSM forms hydrogen bonds with water molecules (in
2NH configurational functional groups), the interfacial region of
the DHPSM bilayer was expected to be in a highly polar environment. The
careful analysis of Laurdan emission spectra through the four-component
deconvolution in this study provides important insights for
understanding the multiple polarity in the lipid membrane.


Last updated on 2020-10-04 at 07:25