Phase Equilibria in DOPC/DPPC-d62/Cholesterol Mixtures Export

@article{citeulike:6102004, abstract = {There is broad interest in the question of fluid-fluid phase coexistence in membranes, in particular, whether evidence for liquid-disordered (l d )-liquid-ordered (l o ) two-phase regions or membrane ” rafts” can be found in natural membranes. In model membrane systems, such phase behavior is observed, and we have used deuterium nuclear magnetic resonance spectroscopy to map the phase boundaries of ternary mixtures containing 1,2-dioleoyl- sn -glycero-3-phosphocholine (DOPC), chain-perdeuterated 1,2-dipalmitoyl- sn -glycero-3-phosphocholine (DPPC-d 62 ), and cholesterol. For both this ternary model system and the binary DPPC-d 62 /cholesterol sytem, we present clear evidence for l d -l o two-phase coexistence. We have selected sample compositions to focus on this region of fluid-fluid phase coexistence and to determine its temperature and composition ranges. The deuterium nuclear magnetic resonance spectra for compositions near the l d -l o phase boundary at high cholesterol concentrations show evidence of exchange broadening or critical fluctuations in composition, similar to that reported by Vist and Davis. There appears to be a line of critical compositions ranging from 48°C for a DOPC/DPPC-d 62 /cholesterol composition of 0:75:25, to −8°C for the composition 57:14:29. At temperatures below this two-phase region, there is a region of three-phase coexistence (l d -l o -gel). These results are collected and presented in terms of a partial ternary phase diagram that is consistent with previously reported results of Vist and Davis.}, author = {Davis, J. and Clair, J. and Juhasz, J.}, citeulike-article-id = {6102004}, citeulike-linkout-0 = {http://dx.doi.org/10.1016/j.bpj.2008.09.042}, citeulike-linkout-1 = {http://linkinghub.elsevier.com/retrieve/pii/S0006349508000532}, day = {21}, doi = {10.1016/j.bpj.2008.09.042}, issn = {00063495}, journal = {Biophysical Journal}, keywords = {fluid, membrane, phase}, month = {January}, number = {2}, pages = {521--539}, posted-at = {2009-11-12 13:51:24}, priority = {2}, title = {Phase Equilibria in DOPC/DPPC-d62/Cholesterol Mixtures}, url = {http://dx.doi.org/10.1016/j.bpj.2008.09.042}, volume = {96}, year = {2009} }

TY - JOUR ID - citeulike:6102004 L3 - citeulike-article-id:6102004 N2 - There is broad interest in the question of fluid-fluid phase coexistence in membranes, in particular, whether evidence for liquid-disordered (l d )-liquid-ordered (l o ) two-phase regions or membrane “rafts” can be found in natural membranes. In model membrane systems, such phase behavior is observed, and we have used deuterium nuclear magnetic resonance spectroscopy to map the phase boundaries of ternary mixtures containing 1,2-dioleoyl- sn -glycero-3-phosphocholine (DOPC), chain-perdeuterated 1,2-dipalmitoyl- sn -glycero-3-phosphocholine (DPPC-d 62 ), and cholesterol. For both this ternary model system and the binary DPPC-d 62 /cholesterol sytem, we present clear evidence for l d -l o two-phase coexistence. We have selected sample compositions to focus on this region of fluid-fluid phase coexistence and to determine its temperature and composition ranges. The deuterium nuclear magnetic resonance spectra for compositions near the l d -l o phase boundary at high cholesterol concentrations show evidence of exchange broadening or critical fluctuations in composition, similar to that reported by Vist and Davis. There appears to be a line of critical compositions ranging from 48°C for a DOPC/DPPC-d 62 /cholesterol composition of 0:75:25, to −8°C for the composition 57:14:29. At temperatures below this two-phase region, there is a region of three-phase coexistence (l d -l o -gel). These results are collected and presented in terms of a partial ternary phase diagram that is consistent with previously reported results of Vist and Davis. IS - 2 JF - Biophysical Journal SN - 00063495 EP - 539 TI - Phase Equilibria in DOPC/DPPC-d62/Cholesterol Mixtures VL - 96 SP - 521 KW - fluid KW - membrane KW - phase AU - Davis, J AU - Clair, J AU - Juhasz, J PY - 2009/01/21/ UR - http://dx.doi.org/10.1016/j.bpj.2008.09.042 ER -