Curvature and bending constants for phosphatidylserine-containing membranes
Curvature and bending constants for phosphatidylserine-containing membranes
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DOI：
10.1016/s0006-3495(03)74596-2
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发表时间：
2003-09-01
影响因子：
3.4
通讯作者：
Rand, RP
中科院分区：
文献类型：
--
作者：
Fuller, N;Benatti, CR;Rand, RP
磷脂酰丝氨酸（PS）是一种具有重要生物相关性的阴离子磷脂，在pH 7.0时在水中形成具有净负表面电荷的多层相。本研究将二油酰IPS（DOPS）与形成反六方（H-II）的磷脂酰乙醇胺（DOPE）混合，用X-射线衍射和渗透应力定量测定其自发曲率（1/R-0 p）和弯曲模量（K-cp）。从5到30摩尔% PS的混合物是稳定的H-II相，条件是还添加16重量%十四烷（td）以减轻链堆积应力。随着DOPS浓度的增加，完全水化的晶格尺寸增加。结构变化的分析给出了1144埃的DOPS的明显R-0 p;符号相反且相对。与DOPE相比（-30埃）。与DOPE相比，H-II相的渗透应力没有检测到DOPS的显著不同的弯曲模量（K-cp）。在pH小于或等于4.0时，DOPS（没有td）通过了自己的H-II相，与以前的结果一致，这表明在丝氨酸头基质子化后曲率逆转。与此相反，当td存在时，DOPS/td形成有限溶胀的层状相，其尺寸随pH增加。DOPS/DOPE/td混合物形成H-II相，其尺寸随pH和DOPS含量增加。对于十四烷，估计将DOPS在pH 2.1下的1/R-0 p置于零。十四烷在低pH下明显影响DOPS的解离度。
Phosphatidylserine (PS), an anionic phospholipid of significant biological relevance, forms a multilamellar phase in water with net negative surface charge at pH 7.0. In this study we mixed dioleoyIPS (DOPS) with reverse hexagonal (H-II)-forming phosphatidylethanolamine (DOPE), and used x-ray diffraction and osmotic stress to quantify its spontaneous curvature (1/R-0p) and bending modulus (K-cp). The mixtures were stable H-II phases from 5 to 30 mol % PS, providing 16 wt % tetradecane (td) was also added to relieve chain-packing stress. The fully hydrated lattice dimension increased with DOPS concentration. Analysis of structural changes gave an apparent R-0p for DOPS of 1144 Angstrom; opposite in sign and relatively. at compared to DOPE (-30 Angstrom). Osmotic stress of the H-II phases did not detect a significantly different bending modulus (K-cp) for DOPS as compared to DOPE. At pH less than or equal to 4.0, DOPS (with no td) adopted the H-II phase on its own, in agreement with previous results, suggesting a reversal in curvature upon protonation of the serine headgroup. In contrast, when td was present, DOPS/td formed a lamellar phase of limited swelling whose dimension increased with pH. DOPS/DOPE/td mixtures formed H-II phases whose dimension increased both with pH and with DOPS content. With tetradecane, estimates put 1/R-0p for DOPS at pH 2.1 at zero. Tetradecane apparently affects the degree of dissociation of DOPS at low pH.