Formation of a Mimetic Biomembrane from the Hydrophobic Protein Zein and Phospholipids: Structure and Application
Formation of a Mimetic Biomembrane from the Hydrophobic Protein Zein and Phospholipids: Structure and Application
复制标题
疏水蛋白玉米醇溶蛋白和磷脂模拟生物膜的形成：结构和应用
DOI：
10.1021/acs.jpcc.7b04573
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发表时间：
2017
期刊：
影响因子：
3.7
通讯作者：
Jin-Ye Wang
中科院分区：
文献类型：
--
作者：
Liping Wang;Toshiaaki Gotoh;Yuzhu Wang;Tsutomu Kouyama;Jin-Ye Wang
α-玉米醇溶蛋白是玉米胚乳中的一种贮藏蛋白，易于大量纯化。将α-玉米醇溶蛋白与磷脂-胆固醇（PC-Chol）脂质体复合。脂质体中α-玉米醇溶蛋白的最大掺入量为0.05%（mol/mol），PC与玉米醇溶蛋白的摩尔比接近2400。当玉米醇溶蛋白的插入量达到此水平时，脂质双层的相变温度几乎不受影响，但当α-玉米醇溶蛋白的加入温度高于相变温度时，阿霉素（DOX）从PC-Chol脂质体中的渗漏明显变慢。PC-胆固醇-玉米醇溶蛋白脂质体的低温透射电子显微镜照片显示，在多层囊泡中的相邻膜通常以约7 nm的规则间隔排列。从同步辐射小角X-射线散射的PC-胆固醇-玉米醇溶蛋白脂质体的数据表明，形成的多层结构与膜间的间隔为7.2 nm，而没有均匀的膜排列中观察到的玉米醇溶蛋白的情况下。假设α-玉米醇溶蛋白具有这样一种伸长的构象，它可以穿透两个相邻的膜层，这就可以很好地解释目前的观察结果。这一特征似乎与最近提出的α-玉米醇溶蛋白超螺旋结构模型相一致。同时，荧光标记的α-玉米醇溶蛋白的实验表明，PC-Chol-Zein脂质体可以被完整的细胞摄取，并定位于细胞内的某些特定区域（可能是内体），而不是在细胞内弥散分布。因此，PC-胆-玉米醇溶蛋白脂质体似乎作为一个有趣的生物膜模型，并可能适用于作为一个药物输送系统。
α-Zein, a storage protein in corn endosperm, could be purified easily and in large amounts. In this study, α-zein was incorporated into phospholipid–cholesterol (PC–Chol) liposomes. The maximal amount of α-zein incorporated in the liposome was 0.05% (mol/mol) and the PC:Zein molar ratio was near 2400. At this level of zein insertion, the phase transition temperature of the lipid bilayer was little affected, but the leakage of doxorubicin (DOX) from the PC–Chol liposome became obviously slower when α-zein was added at a higher temperature than the phase transition temperature. Cryogenic transmission electron micrographs of the PC–Chol–Zein liposome showed that adjacent membranes in multilamellar vesicles were often aligned at a regular interval of about 7 nm. Data from synchrotron small-angle X-ray scattering of the PC–Chol–Zein liposome indicated the formation of the multilamellar structure with an intermembrane interval of 7.2 nm, whereas no homogeneous membrane alignment was observed in the absence of zein. The present observation can be well explained by supposing that α-zein takes on such an elongated conformation that it penetrates through two adjacent membrane layers. This feature seems to be compatible with a recently proposed superhelical structural model of α-zein. Meanwhile, experiments with the fluorescent-labeled α-zein showed that the PC–Chol–Zein liposome could be uptaken by an intact cell and localized in some specialized area (possibly endosomes) within the cell instead of being diffusely distributed in the cell. Thus, the PC–Chol–Zein liposome seems to act as an interesting biomembrane model and may be applicable as a drug delivery system.