Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna 141980, Moscow Region, Russia.
Eur Biophys J. 2013 Aug;42(8):621-9. doi: 10.1007/s00249-013-0910-4. Epub 2013 Jun 1.
In this work we have investigated model lipid mixtures simulating a lipid component of oral stratum corneum (OSC). Neutron diffraction experiments on oriented samples have revealed that SM (bovine brain)/dipalmitoylphosphatidylethanolamine/dipalmitoylphosphatidylcholine (DPPE/DPPC) mixtures at molar ratios of 1/2/1 and 1/1/1 are one-phase membranes. The incorporation of low concentrations of ceramide 6 and cholesterol into SM/DPPC/DPPE bilayers does not result in a phase separation, affecting membrane hydration. The model OSC membrane composed of ceramide 6/cholesterol/fatty acids/cholesterol sulfate/SM (bovine brain)/DPPE/DPPC is characterized by coexistence of several lamellar phases, that behave differently during their hydration in water excess. The phase with lamellar repeat distance of about 45 Å is likely a ceramide-rich phase and shows a restricted swelling in water, while another phase with repeat distance of 50 Å swells very quickly on 15 Å and then disappears. Our results indicate that phospholipid-rich and ceramide-rich domains could possibly coexist in the intercellular space of oral epithelium.
在这项工作中，我们研究了模拟口腔角质层（OSC）脂质成分的模型脂质混合物。对取向样品进行的中子衍射实验表明，SM（牛脑）/二棕榈酰磷脂酰乙醇胺/二棕榈酰磷脂酰胆碱（DPPE/DPPC）摩尔比为 1/2/1 和 1/1/1 的混合物是单相膜。低浓度神经酰胺 6 和胆固醇掺入 SM/DPPC/DPPE 双层膜中不会导致相分离，从而影响膜水合作用。由神经酰胺 6/胆固醇/脂肪酸/胆固醇硫酸盐/SM（牛脑）/DPPE/DPPC 组成的模型 OSC 膜的特征是存在几种层状相，这些相在水过量时的水合过程中表现出不同的行为。层状重复距离约为 45Å 的相可能是富含神经酰胺的相，在水中的溶胀受到限制，而重复距离为 50Å 的另一相在溶胀 15Å 后迅速溶胀，然后消失。我们的结果表明，富含磷脂和富含神经酰胺的区域可能在口腔上皮细胞的细胞间隙中共存。
