TY - JOUR
T1 - Solvatochromic Modeling of Laurdan for Multiple Polarity Analysis of Dihydrosphingomyelin Bilayer
AU - Watanabe, Nozomi
AU - Goto, Yuka
AU - Suga, Keishi
AU - Nyholm, Thomas K.M.
AU - Slotte, J. Peter
AU - Umakoshi, Hiroshi
N1 - Funding Information:
This work was primarily supported by the Japan Society for the Promotion of Science KAKENHI Grant-in-Aids for Scientific Research (A) ( 26249116 ), Grant-in-Aids for Young Scientists (B) ( 16K18279 ), and Grant-in-Aids for Challenging Exploratory Research ( T15K142040 ). N.W. expresses her gratitude for a Japan Society for the Promotion of Science Research Fellowship (JP18J11666) and Tobitate! (Leap for Tomorrow) Young Ambassador Program . The Slotte laboratory was supported by generous funds from the Sigrid Juselius Foundation .
Funding Information:
This work was primarily supported by the Japan Society for the Promotion of Science KAKENHI Grant-in-Aids for Scientific Research (A) (26249116), Grant-in-Aids for Young Scientists (B) (16K18279), and Grant-in-Aids for Challenging Exploratory Research (T15K142040). N.W. expresses her gratitude for a Japan Society for the Promotion of Science Research Fellowship (JP18J11666) and Tobitate! (Leap for Tomorrow) Young Ambassador Program. The Slotte laboratory was supported by generous funds from the Sigrid Juselius Foundation.
Publisher Copyright:
© 2019 Biophysical Society
PY - 2019/3/5
Y1 - 2019/3/5
N2 - 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 T m 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.
AB - 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 T m 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.
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U2 - 10.1016/j.bpj.2019.01.030
DO - 10.1016/j.bpj.2019.01.030
M3 - Article
C2 - 30819567
AN - SCOPUS:85061928458
VL - 116
SP - 874
EP - 883
JO - Biophysical Journal
JF - Biophysical Journal
SN - 0006-3495
IS - 5
ER -