TY - JOUR
T1 - Deuterium NMR of Raft Model Membranes Reveals Domain-Specific Order Profiles and Compositional Distribution
AU - Yasuda, Tomokazu
AU - Tsuchikawa, Hiroshi
AU - Murata, Michio
AU - Matsumori, Nobuaki
N1 - Funding Information:
The authors thank Drs. Yuichi Umegawa and Naoya Inazumi, Osaka University, in our department for help in 2 H NMR measurements. This work was supported by Grants-in-Aid for Scientific Research (A) (No. 25242073 ) from MEXT, Japan ; a grant from the Suntory Institute for Bioorganic Research, Japan ; and the ERATO “Lipid Active Structure Project” from the Japan Science and Technology Agency (JST) . T.Y. as a JSPS fellow is grateful to the Japan Society for the Promotion of Science.
Publisher Copyright:
© 2015 Biophysical Society.
PY - 2015/5/19
Y1 - 2015/5/19
N2 - In this report, we applied site-specifically deuterated N-stearoylsphingomyelins (SSMs) to raft-exhibiting ternary mixtures containing SSM, 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), and cholesterol (Chol) and successfully acquired deuterium quadrupole coupling profiles of SSM from liquid-ordered (Lo) and liquid-disordered (Ld) domains. To our knowledge, this is the first report that shows detailed lipid chain dynamics separately and simultaneously obtained from coexisting Lo and Ld domains. We also found that the quadrupole profile of the Lo phase in the ternary system was almost identical to that in the SSM-Chol binary mixture, suggesting that the order profile of the binary system is essentially applicable to more complicated membrane systems in terms of the acyl chain order. We also demonstrated that 2H NMR spectroscopy, in combination with organic synthesis of deuterated components, could be used to reveal the accurate mole fractions of each component distributed in the Lo and Ld domains. As compared with the reported tie-line analysis of phase diagrams, the merit of our 2H NMR analysis is that the domain-specific compositional fractions are directly attainable without experimental complexity and ambiguity. The accurate compositional distributions as well as lipid order profiles in ternary mixtures are relevant to understanding the molecular mechanism of lipid raft formation.
AB - In this report, we applied site-specifically deuterated N-stearoylsphingomyelins (SSMs) to raft-exhibiting ternary mixtures containing SSM, 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), and cholesterol (Chol) and successfully acquired deuterium quadrupole coupling profiles of SSM from liquid-ordered (Lo) and liquid-disordered (Ld) domains. To our knowledge, this is the first report that shows detailed lipid chain dynamics separately and simultaneously obtained from coexisting Lo and Ld domains. We also found that the quadrupole profile of the Lo phase in the ternary system was almost identical to that in the SSM-Chol binary mixture, suggesting that the order profile of the binary system is essentially applicable to more complicated membrane systems in terms of the acyl chain order. We also demonstrated that 2H NMR spectroscopy, in combination with organic synthesis of deuterated components, could be used to reveal the accurate mole fractions of each component distributed in the Lo and Ld domains. As compared with the reported tie-line analysis of phase diagrams, the merit of our 2H NMR analysis is that the domain-specific compositional fractions are directly attainable without experimental complexity and ambiguity. The accurate compositional distributions as well as lipid order profiles in ternary mixtures are relevant to understanding the molecular mechanism of lipid raft formation.
UR - http://www.scopus.com/inward/record.url?scp=84930001051&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84930001051&partnerID=8YFLogxK
U2 - 10.1016/j.bpj.2015.04.008
DO - 10.1016/j.bpj.2015.04.008
M3 - Article
C2 - 25992728
AN - SCOPUS:84930001051
SN - 0006-3495
VL - 108
SP - 2502
EP - 2506
JO - Biophysical Journal
JF - Biophysical Journal
IS - 10
ER -