Molecular organization of cholesterol in polyunsaturated phospholipid membranes: a solid state 2H NMR investigation

AbstractWe compared the molecular organization of equimolar [3α-2H1]cholesterol in 18:0-18:1PC (1-stearoyl-2-oleoylphosphatidylcholine), 18:0-22:6PC (1-stearoyl-2-docosahexaenoylphosphatidylcholine), 18:0-20:4PC (1-stearoyl-2-arachidonylphosphatidylcholine) and 20:4-20:4PC (1,2-diarachidonylphosphatidylcholine) bilayers by solid state 2H NMR. Essentially identical quadrupolar splittings (Δνr=45±1 kHz) corresponding to the same molecular orientation characterized by tilt angle α0=16±1° were measured in 18:0-18:1PC, 18:0-22:6PC and 18:0-20:4PC. A profound difference in molecular interaction with dipolyunsaturated 20:4-20:4PC, in contrast, is indicated for the sterol. Specifically, the tilt angle α0=22±1° (derived from Δνr=37±1 kHz) is greater and its membrane intercalation is only 15 mol%