Chain asymmetry alters thermotropic and barotropic properties of phospholipid bilayer membranes.
The alignment of the sn-1 and sn-2 acyl chains at the terminal methyl ends generally produces significant influence on the thermodynamic properties of the bilayer phase transitions. We investigated the bilayer phase behavior of asymmetric phospholipids, myristoylpalmitoylphosphatidylcholine and palmitoylmyristoylphosphatidylcholine, by high-pressure light-transmittance and Prodan-fluorescence techniques and differential scanning calorimetry. Constructed temperature-pressure phase diagrams revealed that no stable Lbeta' phase can exist in the whole pressure range because of the formation of the most stable Lc phase. Nevertheless, the pretransition, the detection of which is severely hampered by the exceptionally prompt formation of the Lc phase, was successfully observed. Moreover, the effect of the total and difference of the sn-1 and sn-2 acyl chain lengths on minimal interdigitation pressure (MIP) was summarized in a MIP vs. chain-length inequivalence parameter plot, where the effect was proved to be classified in three zones depending on the alignment of both terminal methyl ends.
Goto
Masaki
M
Department of Life System, Institute of Technology and Science, The University of Tokushima, 2-1 Minamijosanjima-cho, Tokushima 770-8506, Japan.
Ishida
Shunsuke
S
Tamai
Nobutake
N
Matsuki
Hitoshi
H
Kaneshina
Shoji
S
D015081:2-Naphthylamine / Q000031:analogs & derivatives / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D002784:Cholesterol / Q000378:metabolism / Q000502:physiology; D006874:Hydrostatic Pressure; D008051:Lipid Bilayers / Q000737:chemistry*; D044367:Phase Transition; D010743:Phospholipids / Q000737:chemistry*; D011312:Pressure; D013329:Structure-Activity Relationship; D013696:Temperature; D013816:Thermodynamics
D008051:Lipid Bilayers; D010743:Phospholipids; C038517:prodan; D002784:Cholesterol; D015081:2-Naphthylamine