Effects of chemical modification of sphingomyelin ammonium group on formation of liquid-ordered phase.
Sphingomyelin (SM) and cholesterol form microdomains called lipid rafts in cellular membranes. To develop a versatile fluorescent lipid probe, chemical modifications to both the hydrophobic and hydrophilic portions of SM are essential. Few reports describing SM probes with a fluorophore at the polar head group have been published. This study examined the effect of substitution on an ammonium moiety of SM on the membrane properties of SM. Two SM analogs with small propargyl and allyl groups on the quaternary nitrogen atom were synthesized and subjected to analysis using differential scanning calorimetry, fluorescent anisotropy, detergent solubilization, surface pressure, and density measurements. Results demonstrated that the two SM analogs retained the membrane properties of SM, including formation of an ordered phase and the ability to interact with cholesterol. A dansyl-substituted SM was prepared for fluorescent measurements. Dansyl-SM showed less of a propensity to form microdomains. These findings imply the potential application of N-substituted SMs as a raft-specific molecular probe.
Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.
Sarah A
SA
Goretta
Masanao
M
Kinoshita
Shoko
S
Mori
Hiroshi
H
Tsuchikawa
Nobuaki
N
Matsumori
Michio
M
Murata
D002152:Calorimetry, Differential Scanning; D002784:Cholesterol / Q000378:metabolism; D003619:Dansyl Compounds / Q000737:chemistry; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D021962:Membrane Microdomains / Q000737:chemistry / Q000378:metabolism; D009584:Nitrogen / Q000737:chemistry; D044367:Phase Transition; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013109:Sphingomyelins / Q000737:chemistry* / Q000378:metabolism; D044366:Transition Temperature
D003619:Dansyl Compounds; D005456:Fluorescent Dyes; D000644:Quaternary Ammonium Compounds; D013109:Sphingomyelins; D002784:Cholesterol; D009584:Nitrogen; C029038:dansyl chloride