Structural characterization of styrene-maleic acid copolymer-lipid nanoparticles (SMALPs) using EPR spectroscopy
Structural characterization of styrene-maleic acid copolymer-lipid nanoparticles (SMALPs) using EPR spectroscopy
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DOI：
10.1016/j.chemphyslip.2019.02.003
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发表时间：
2019-05-01
影响因子：
3.4
通讯作者：
Lorigan, Gary A.
中科院分区：
文献类型：
--
作者：
Bali, Avnika P.;Sahu, Indra D.;Lorigan, Gary A.
膜蛋白（MP）的光谱研究是具有挑战性的，由于在制备均匀的和功能性的脂质膜模拟系统，膜蛋白可以正确地折叠和功能的困难。最近的研究表明，苯乙烯-马来酸（SMA）共聚物作为一种大分子表面活性剂，因此有助于形成盘形脂质双层纳米颗粒（苯乙烯-马来酸共聚物-脂质纳米颗粒（SMALP）），保留天然脂质膜的结构特征。我们以前已经报道了使用可逆加成-断裂链转移（RAFT）聚合的SMA嵌段共聚物的受控合成，并且苯乙烯与马来酸的重量比的改变影响纳米颗粒尺寸。与用于市售SMA的常规自由基聚合技术相比，RAFT合成提供了对SMA聚合物结构的上级控制。然而，脂双层和增溶RAFT合成的SMA聚合物之间的相互作用目前还没有完全了解。在这项研究中，EPR光谱被用来检测的酰基链上的扰动后，通过将基于PC的氮氧自由基自旋标记物连接到第5，第12，和第16位沿着的脂双层的酰基链引入RAFT合成的SMA聚合物。EPR谱显示，与其他两个区域相比，在第12位处具有高刚性，显示出与通过常规方法合成的市售聚合物相似的品质。此外，中心EPR线宽和相关时间的数据得到了与以前的研究结果是一致的。
Spectroscopic studies of membrane proteins (MPs) are challenging due to difficulties in preparing homogenous and functional lipid membrane mimetic systems into which membrane proteins can properly fold and function. It has recently been shown that styrene-maleic acid (SMA) copolymers act as a macromolecular surfactant and therefore facilitate the formation of disk-shaped lipid bilayer nanoparticles (styrene-maleic acid copolymer-lipid nanoparticles (SMALPs)) that retain structural characteristics of native lipid membranes. We have previously reported controlled synthesis of SMA block copolymers using reversible addition-fragmentation chain transfer (RAFT) polymerization, and that alteration of the weight ratio of styrene to maleic acid affects nanoparticle size. RAFT-synthesis offers superior control over SMA polymer architecture compared to conventional radical polymerization techniques used for commercially available SMA. However, the interactions between the lipid bilayer and the solubilized RAFT-synthesized SMA polymer are currently not fully understood. In this study, EPR spectroscopy was used to detect the perturbation on the acyl chain upon introduction of the RAFT-synthesized SMA polymer by attaching PC-based nitroxide spin labels to the 5th, 12th, and 16th positions along the acyl chain of the lipid bilayer. EPR spectra showed high rigidity at the 12th position compared to the other two regions, displaying similar qualities to commercially available polymers synthesized via conventional methods. In addition, central EPR linewidths and correlation time data were obtained that are consistent with previous findings.