Slotte J P, Ostman A L, Kumar E R, Bittman R
Department of Biochemistry and Pharmacy, Abo Akademi University, Turku, Finland.
Biochemistry. 1993 Aug 10;32(31):7886-92. doi: 10.1021/bi00082a008.
Pure and mixed monolayers of mono- and dihexoside cerebrosides with cholesterol have been characterized at the air/water interface. Cholesterol oxidase was used as a reporter enzyme for the cholesterol-cerebroside interaction in the mixed monolayers. The cerebrosides either were derived from bovine brain extracts or were synthetic. The dihexoside cerebrosides were synthesized by coupling of the hepta-O-acetyl-alpha-lactosyl- or maltosylphosphoramidates with D-erythro-N-acylceramides in dichloromethane, in the presence of trimethylsilyl triflate and molecular sieves, followed by hydrolysis of the acetate-protecting groups. All of the bovine-brain-derived cerebrosides [galactosyl cerebroside (GalCer, types I and II), glucosyl cerebroside (GlcCer), and lactosyl cerebroside (LacCer)] had very condensed force-area isotherms (compressibility values of 3-5 x 10(-3) m/mN at 20 mN/m), as did the synthetic N-stearoylmaltosylceramide (N-18:0 MaltCer). Shorter-chain synthetic cerebrosides (N-8:0 LacCer and N-8:0 MaltCer) had more expanded isotherms, with compressibility values of 15-17 x 10(-3) m/mN. When cholesterol was included in mixed monolayers of monohexoside cerebroside, it did not induce significant condensation of packing (indicating that cholesterol did not increase the order of the acyl chains). However, with dihexoside cerebrosides, a cholesterol-induced condensing effect was observed, which amounted to a 11-19% reduction in the observed mean molecular area. When cholesterol oxidase was used to titrate the stoichiometry of cholesterol/cerebroside in mixed monolayers, at which pure cholesterol clusters appeared, it was observed that in monohexoside cerebroside monolayers cholesterol clusters were present even below a 1:1 molar stoichiometry.(ABSTRACT TRUNCATED AT 250 WORDS)
已对单己糖脑苷脂和二己糖脑苷脂与胆固醇的纯单层和混合单层在空气/水界面进行了表征。胆固醇氧化酶用作混合单层中胆固醇 - 脑苷脂相互作用的报告酶。脑苷脂要么来源于牛脑提取物，要么是合成的。二己糖脑苷脂是通过在二氯甲烷中，在三氟甲磺酸三甲基硅酯和分子筛存在下，将七 - O - 乙酰 - α - 乳糖基 - 或麦芽糖基磷酰胺与D - 赤藓糖 - N - 酰基神经酰胺偶联，然后水解乙酸保护基团合成的。所有源自牛脑的脑苷脂[半乳糖基脑苷脂（GalCer，I型和II型）、葡萄糖基脑苷脂（GlcCer）和乳糖基脑苷脂（LacCer）]都具有非常紧密的力 - 面积等温线（在20 mN/m时压缩率值为3 - 5×10⁻³ m/mN），合成的N - 硬脂酰麦芽糖基神经酰胺（N - 18:0 MaltCer）也是如此。较短链的合成脑苷脂（N - 8:0 LacCer和N - 8:0 MaltCer）具有更扩展的等温线，压缩率值为15 - 17×10⁻³ m/mN。当胆固醇包含在单己糖脑苷脂的混合单层中时，它不会引起显著的堆积凝聚（表明胆固醇不会增加酰基链的有序性）。然而，对于二己糖脑苷脂，观察到胆固醇诱导的凝聚效应，这导致观察到的平均分子面积减少了11 - 19%。当使用胆固醇氧化酶滴定混合单层中胆固醇/脑苷脂的化学计量比时，在出现纯胆固醇簇的情况下，观察到在单己糖脑苷脂单层中，即使在摩尔化学计量比低于1:1时也存在胆固醇簇。
