The kinetics of non-lamellar phase formation in DOPE-Me: relevance to biomembrane fusion.
The mechanism of the lamellar/inverted cubic (QII) phase transition is related to that of membrane fusion in lipid systems. N-Monomethylated dioleoylphosphatidylethanolamine (DOPE-Me) exhibits this transition and is commonly used to investigate the effects of exogenous substances, such as viral fusion peptides, on the mechanism of membrane fusion. We studied DOPE-Me phase behavior as a first step in evaluating the effects of membrane-spanning peptides on inverted phase formation and membrane fusion. These measurements show that: a) the onset temperatures for QII and inverted hexagonal (HII) phase formation both are temperature scan rate-dependent; b) longer pre-incubation times at low temperature and lower temperature scan rates favor formation of the QII phase; and c) in temperature-jump experiments between 61 and 65 degrees C, the meta-stable HII phase forms initially, and disappears slowly while the QII phase develops. These observations are rationalized in the context of a mechanism for both the lamellar/non-lamellar phase transition and the related process of membrane fusion.
Cherezov
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V
Biochemistry, Biophysics and Chemistry, The Ohio State University, 100W 18th Ave., Columbus, OH 43210, USA.
Siegel
D P
DP
Shaw
W
W
Burgess
S W
SW
Caffrey
M
M
D002152:Calorimetry, Differential Scanning; D002855:Chromatography, Thin Layer; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry; D008561:Membrane Fusion; D008823:Micelles; D008958:Models, Molecular; D044367:Phase Transition; D010714:Phosphatidylethanolamines / Q000737:chemistry*; D014961:X-Ray Diffraction
D008051:Lipid Bilayers; D008081:Liposomes; D008823:Micelles; D010714:Phosphatidylethanolamines