title: Detailed comparison of deuterium quadrupole profiles between sphingomyelin and phosphatidylcholine bilayers.
abstract: Lipid rafts are microdomains rich in sphingomyelin (SM) and cholesterol (Chol). The essential question is why natural lipid rafts prefer SM rather than saturated diacyl glycerophosphocholine, although both form ordered membranes with Chol in model systems. Hence in this study, we synthesized site-specifically deuterated 1-palmitoyl-2-stearoyl-sn-glycero-3-phosphocholines that match the acyl chain length of stearoyl-SM (SSM), and compared their deuterium quadrupole coupling profiles in detail. The results suggest a deeper distribution of Chol in the SSM membranes, a lower entropic penalty upon accommodation of Chol in SSM membranes, and a higher thermal stability of acyl-chain orders in the SSM-Chol bilayers than in the 1-palmitoyl-2-stearoyl-sn-glycero-3-phosphocholine-Chol system at various Chol concentrations. The entropy effect and thermal stability should render SM a more preferred raft constituent than saturated diacyl glycerophosphocholine. Our data also demonstrate that the selective and comprehensive deuteration strategy is indispensable for accurate comparison of order profiles.
authors: Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan; Japan Science and Technology Agency, ERATO, Lipid Active Structure Project, Toyonaka, Osaka, Japan.
authors: Tomokazu
authors: T
authors: Yasuda
authors: Japan Science and Technology Agency, ERATO, Lipid Active Structure Project, Toyonaka, Osaka, Japan.
authors: Masanao
authors: M
authors: Kinoshita
authors: Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan; Japan Science and Technology Agency, ERATO, Lipid Active Structure Project, Toyonaka, Osaka, Japan.
authors: Michio
authors: M
authors: Murata
authors: Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan. Electronic address: matsmori@chem.sci.osaka-u.ac.jp.
authors: Nobuaki
authors: N
authors: Matsumori
mesh_terms: D002784:Cholesterol / Q000737:chemistry*; D003903:Deuterium / Q000737:chemistry*; D019277:Entropy; D008051:Lipid Bilayers / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry*; D013109:Sphingomyelins / Q000737:chemistry*
chemical_list: D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D013109:Sphingomyelins; D002784:Cholesterol; D003903:Deuterium