Sterols play important roles in membrane organization and functions. Model membranes containing cholesterol reveal that the addition of cholesterol in lipid membranes results in sterol-poor and sterol-rich domains. The sterol-rich domain, in the liquid-ordered phase, is thought to be the lipid raft found in cell membranes. On the other hand, in some model membranes liquid-ordered phase is not observed. In this work, we investigate the effect of stigmasterol on the physical properties 1-palmitoyl-d31-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE-d31) membranes.
Model membranes composed of POPE-d31 and stigmasterol were studied using deuterium nuclear magnetic resonance. NMR spectra were taken as a function of temperature and stigmasterol concentration up to 50 mol %. Stigmasterol decreases membrane order of the gel-phase POPE-d31 bilayers and this effect is very limited. In contrast, stigmasterol increases the chain order of the liquid-crystalline (lc) phase POPE-d31 bilayers slightly. The temperature-composition phase diagram is presented. The addition of stigmasterol does not affect the gel-to-lc phase transition significantly, however it decreases the temperature of lc-to-HII phase transition strongly. In addition, there is no liquid-ordered phase observed in POPE-d31/stigmasterol membranes. A comparison between stigmasterol and other sterols suggest that the extra double bond and the extra methyl group in the acyl chain of sterol hinder the ability of sterol to increase POPE-d31 chain order.
 L. J. Pike. The Challenge of Lipid Rafts. Journal of Lipid Research 50 (2009) S323-S328.
 S. J. Singer and G. L. Nicolson. 1972. The Fluid Mosaic Model of the Structure of the Cell Membranes. Science 175:720-731.
 Kai Simons and Elina Ikonen. 1997. Functional Rafts in Cell Membranes. Nature 387: 569-572.
 Kai Simons and Julio L. Sampaio. 2011. Membrane Organization and Lipid Rafts. Cold Spring Harb Perspect Biol 3:a004697
 D. A. Brown and E. London. 1998. Functions of Lipid Rafts in Biological Membranes. Annu. Rev. Cell Dev. Biol. 14, 111-36.
 K. Simons and E. Ikonen. 2000. How Cell Handle Cholesterol. Science 290:1721-1726.
 John F. Nagle, Stephanie Tristram-Nagle. 2000. Structure of Lipid Bilayers. Biochim. Biophys. Acta. 1469: 159-195.
 J. Rubenstein, B. A. Smith, and H. M. McConnell. 1979. Lateral diffusion in Binary Mixtures of cholesterol and phosphatidylcholines. Proc. Natl. Acad. Sci. 76: 15-18.
 Sean Munro. 2003. Lipid Rafts: Elusive or Illusive? Cell 115: 377-388.
 C. Tanford. 1980. The Hydrophobic Effect, 2nd ed., Wiley, New York.
 Emil Endress, Sybille Bayerl, Katrin Prechtel, Christian Maier, Rudolf Merkel, and Thomas M. Bayerl. 2002. The Effect of Cholesterol, Lanosterol, and Ergosterol on Lecithin Bilayer Mechanical Properties at Molecular and Microscopic Dimensions: A Solid-State NMR and Micropipet Study. Langmuir 18: 3293-3299
 X. Xu, and E. London. 2000. The Effect of Sterol Structure on Membrane Lipid Domains Reveals How Cholesterol Can Induce Lipid Domain Formation. Biochemistry 39:843-849.
 Chantal Pare´ and Michel Lafleur. 1998. Polymorphism of POPE/Cholesterol System: A 2H Nuclear Magnetic Resonance and Infrared Spectroscopic Investigation. Biophysical Journal 74:899-909.
 Ya-Wei Hsueh, Chi-Jung Weng, Mei-Ting Chen, Jenifer Thewalt, and Martin Zuckermann. 2010. Deuterium NMR Study of the Effect of Ergosterol on POPE Membranes. Biophysical Journal 98:1209-1217.
 Philip L. Ywagle. The Structure of Biological Membranes, 2nd ed., CRC PRESS.
 C. Santivarangkna, U. Kulozik and P. Foerst. 2008. Inactivation mechanisms of lactic acid starter cultures preserved by drying processes. Journal of Applied Microbiology 105:1-13.
 Ya-Wei Hsueh, Ralph Giles, Neil Kitson, and Jenifer Thewalt. 2002. The Effect of Ceramide on Phosphatidylcholine Membranes: A Deuterium NMR Study. Biophys. J. 82:3089－3095.
 Davis, J. H., and K. R. Jeffrey. 1977. The temperature dependence of chain order in potassium palmitate-water. A deuterium NMR study. Chem. Phys. Lipids. 20:87－104.
 Davis, J. H., K. R. Jeffrey, …, T. P. Higgs. 1976. Quadrupolar echo deuteron magnetic resonance spectroscopy in ordered hydrocarbon chains. Chem. Phys. Lett. 42:390－394.
 Lafleur, M., Fine, B., Sternin, E., Cullis, P. R., and Bloom, M. 1989. Smoothed orientational order profile of lipid bilayers by 2H-nuclear magnetic resonance. Biophys. J. 56:1037－1041.
 Lafleur, M., P. R. Cullis, …, M. Bloom. 1990. Comparison of the orientational order of lipid chains in the Lα and HII phases. Biochemistry. 29:8325–8333.