Denisov I G, Grinkova Y V, Lazarides A A, Sligar S G
Departments of Biochemistry and Chemistry and the Beckman Institute, University of Illinois, Urbana, Illinois 61801, USA.
J Am Chem Soc. 2004 Mar 24;126(11):3477-87. doi: 10.1021/ja0393574.
Using a recently described self-assembly process (Bayburt, T. H.; Grinkova, Y. V.; Sligar, S. G. Nano Letters 2002, 2, 853-856), we prepared soluble monodisperse discoidal lipid/protein particles with controlled size and composition, termed Nanodiscs, in which the fragment of dipalmitoylphosphatidylcholine (DPPC) bilayer is surrounded by a helical protein belt. We have customized the size of these particles by changing the length of the amphipathic helical part of this belt, termed membrane scaffold protein (MSP). Herein we describe the design of extended and truncated MSPs, the optimization of self-assembly for each of these proteins, and the structure and composition of the resulting Nanodiscs. We show that the length of the protein helix surrounding the lipid part of a Nanodisc determines the particle diameter, as measured by HPLC and small-angle X-ray scattering (SAXS). Using different scaffold proteins, we obtained Nanodiscs with the average size from 9.5 to 12.8 nm with a very narrow size distribution (+/-3%). Functionalization of the N-terminus of the scaffold protein does not perturb their ability to form homogeneous discoidal structures. Detailed analysis of the solution scattering confirms the presence of a lipid bilayer of 5.5 nm thickness in Nanodiscs of different sizes. The results of this study provide an important structural characterization of self-assembled phospholipid bilayers and establish a framework for the design of soluble amphiphilic nanoparticles of controlled size.
利用最近描述的一种自组装方法（Bayburt, T. H.; Grinkova, Y. V.; Sligar, S. G. 《纳米快报》2002年，第2卷，853 - 856页），我们制备了具有可控尺寸和组成的可溶性单分散盘状脂质/蛋白质颗粒，称为纳米盘，其中二棕榈酰磷脂酰胆碱（DPPC）双层片段被一条螺旋蛋白质带包围。我们通过改变这条带的两亲性螺旋部分（称为膜支架蛋白，MSP）的长度来定制这些颗粒的大小。在此，我们描述了延伸和截短的MSP的设计、每种蛋白质自组装的优化以及所得纳米盘的结构和组成。我们表明，通过高效液相色谱（HPLC）和小角X射线散射（SAXS）测量，围绕纳米盘脂质部分的蛋白质螺旋长度决定了颗粒直径。使用不同的支架蛋白，我们获得了平均尺寸从9.5到12.8 nm且尺寸分布非常窄（±3%）的纳米盘。支架蛋白N端的功能化不会干扰其形成均匀盘状结构的能力。对溶液散射的详细分析证实，不同大小的纳米盘中存在厚度为5.5 nm的脂质双层。这项研究的结果提供了自组装磷脂双层的重要结构表征，并建立了设计可控尺寸的可溶性两亲性纳米颗粒的框架。
