title: What determines the thickness of a biological membrane.
abstract: Membrane thickness is thought to play a key role in protein function. Thus understanding the cell's ability to modulate the thickness of its membranes is essential in elucidating the structure/function relationship in biological membranes. We have investigated the influence of cholesterol on the structure of "thin" (diC14:1PC) and "thick" (diC22:1PC) phospholipid bilayers using oriented multibilayers and small angle neutron diffraction. Neutron contrast variation was used to determine the structure factors and the distribution of water across the bilayers. We found that in response to cholesterol, bilayer thickness changed in a similar fashion in both systems. The thickening of bilayers was rationalized in terms of cholesterol's ordering effect on the lipid's acyl chains, which dominates over the other option of rectifying the hydrophobic mismatch, surprisingly even in the case of diC22:1PC and cholesterol.
authors: Canadian Neutron Bean Center, National Research Council, Chalk River, Ontario K0J 1P0, Canada. norbert.kucerka@nrc.gc.ca
authors: Norbert
authors: N
authors: Kucerka
authors: Mu-Ping
authors: MP
authors: Nieh
authors: Jeremy
authors: J
authors: Pencer
authors: Jonathan N
authors: JN
authors: Sachs
authors: John
authors: J
authors: Katsaras
mesh_terms: D000465:Algorithms; D002784:Cholesterol / Q000737:chemistry*; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D016014:Linear Models; D008051:Lipid Bilayers / Q000737:chemistry*; D033363:Neutron Diffraction; D010713:Phosphatidylcholines / Q000737:chemistry*; D011336:Probability; D053838:Scattering, Small Angle; D014867:Water / Q000737:chemistry
chemical_list: D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D014867:Water; C500050:1,2-dierucoyl phosphatidylcholine; D002784:Cholesterol; D004134:Dimyristoylphosphatidylcholine