Cholesterol decreases the interfacial elasticity and detergent solubility of sphingomyelins

被引：129

作者：

Li, XM ^{[1
]}

Momsen, MM ^{[1
]}

Smaby, JM ^{[1
]}

Brockman, HL ^{[1
]}

Brown, RE ^{[1
]}

机构：

[1] Univ Minnesota, Hormel Inst, Austin, MN 55912 USA

来源：

BIOCHEMISTRY | 2001年 / 40卷 / 20期

关键词：

D O I：

10.1021/bi002791n

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

The interfacial interactions of cholesterol with sphingomyelins (SMs) containing various homogeneous acyl chains have been investigated by Langmuir film balance approaches. Low in-plane elasticity among the packed lipids was identified as an important physical feature of the cholesterol-sphingomyelin liquid-ordered phase that correlates with detergent resistance, a characteristic property of sphingolipid-sterol. rafts. Changes in the in-plane elastic packing, produced by cholesterol, were quantitatively assessed by the surface compressional moduli (C-s(-1)) of the monolayer isotherms. Of special interest were C-s(-1) values determined at high surface pressures (>30 mN/m) that mimic the biomembrane situation. To identify structural features that uniquely affect the in-plane elasticity of the sphingomyelin-cholesterol lateral interaction, comparisons were made with phosphatidylcholine (PC)-cholesterol mixtures. Cholesterol markedly decreased the in-plane elasticity of either SM or PC regardless of whether they were fluid or gel phase without cholesterol, The magnitude of the reduction in in-plane elasticity induced by cholesterol was strongly influenced by acyl chain structure and by interfacial functional groups. Liquid-ordered phase formed at lower cholesterol mole fractions when SM's acyl chain was saturated rather than monounsaturated. At similar high cholesterol mole fractions, the in-plane elasticity within SM-cholesterol liquid-ordered phase was significantly lower than that of PC-cholesterol liquid-ordered phase, even when PCs were chain-matched to the SMs, Sphingoid-base functional groups (e.g., amide linkages), which facilitate or strengthen intermolecular hydrogen bonds, appear to be important for forming sphingomyelin-cholesterol, liquid-ordered phases with especially low in-plane elasticity. The combination of structural features that predominates in naturally occurring SMs permits very effective resistance to solubilization by Triton X-100.

引用

页码：5954 / 5963

页数：10

共 70 条

[1] On the origin of sphingolipid/cholesterol-rich detergent-insoluble cell membranes: Physiological concentrations of cholesterol and sphingolipid induce formation of a detergent-insoluble, liquid-ordered lipid phase in model membranes [J].