Calcium-Induced Formation of Subdomains in Phosphatidylethanolamine-Phosphatidylglycerol Bilayers: A Combined DSC, 31P NMR, and AFM Study
Calcium-Induced Formation of Subdomains in Phosphatidylethanolamine-Phosphatidylglycerol Bilayers: A Combined DSC, 31P NMR, and AFM Study
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DOI：
10.1021/jp8102468
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发表时间：
2009-04-09
影响因子：
3.3
通讯作者：
Hernandez-Borrell, Jordi
中科院分区：
文献类型：
--
作者：
Picas, Laura;Montero, M. Teresa;Hernandez-Borrell, Jordi
本文研究了Ca ~（2+）对1-棕榈酰-2-油酰-sn-甘油-3-磷酸乙醇胺（POPE）和1-棕榈酰-2-油酰-sn-甘油-3-磷酸甘油（POPG）（3：1，mol/mol）侧向分离的影响。用原子力显微镜（AFM）观察了支撑的脂质双层（SLB）。由于SLB是由POPETOPG的脂质体形成的，我们通过差示扫描量热法（DSC）和P-31核磁共振光谱（P-31 NMR）研究了钙对这些悬浮液的影响。AFM图像显示存在两个分离的相，较高的显示具有突出子域的区域。应用力谱（FS）来澄清每个相的性质。将从力曲线中提取的穿透力（F-y）、粘附力（F-adh）和高度值分配给相应的凝胶（L-beta）和流体（L-alpha）相。通过DSC得到的吸热表明，在Ca 2+的存在下，相分离已经存在于用于形成SLB的POPETOPG的悬浮液中。由于在制备SLB期间施加的温度变化，进行P-31 NMR研究以在将样品铺展到云母上之前评估样品的层状性质。与原位AFM实验，我们表明，结合的Ca 2 + POPG富集域只诱导L-β相的亚结构域的形成。
We study the effect of Ca2+ on the lateral segregation of 1-palmitoyl-2-oleoyi-sn-glycero-3-phosphoethanolamine (POPE) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) (3:1, mol/mol). Supported lipid bilayers (SLBs) were observed by atomic force microscopy (AFM). Since SLBs are formed from liposomes of POPETOPG, we examined the effect of calcium on these suspensions by differential scanning calorimetry (DSC) and P-31 nuclear magnetic resonance spectroscopy (P-31 NMR). AFM images revealed the existence of two separated phases, the higher showing a region with protruding subdomains. Force spectroscopy (FS) was applied to clarify the nature of each phase. The values of breakthrough force (F-y), adhesion force (F-adh), and height extracted from the force curves were assigned to the corresponding gel (L-beta) and fluid (L-alpha) phase. The endotherms obtained by DSC Suggest that, in the presence of Ca2+, phase separation already exists in the suspensions of POPETOPG used to form SLBs. Due to the temperature changes applied during preparation of SLBs a P-31 NMR study was performed to assess the lamellar nature of the samples before spreading them onto mica. With in situ AFM experiments we showed that the binding of Ca2+ to POPG-enriched domains only induces the formation of subdomains in the L-beta phase.