Wallace B A, Janes R W
Department of Chemistry, Rensselaer Polytechnic Institute, Troy, NY 12180.
J Mol Biol. 1991 Feb 20;217(4):625-7. doi: 10.1016/0022-2836(91)90520-g.
Single crystals of a complex of gramicidin A, a transmembrane channel-forming polypeptide, and dipalmitoyl phosphatidylcholine, a phospholipid, have been prepared and characterized by X-ray diffraction. They belong to space group P222(1), with unit cell dimensions a = 26.8 A, b = 27.5 A, c = 32.8 A. The asymmetric unit appears to be a complex of one gramicidin monomer and two phospholipid molecules. The unit cell dimensions, space group, and chemical composition are compatible with lipids packing in a bilayer-like motif, and an end-to-end association of gramicidin monomers to form a functional dimeric unit. The crystals diffract to 2 A and are suitable for structural studies by single-crystal X-ray analysis. This represents the first example of a well-ordered crystalline channel complexed with lipids, and solution of its structure may give insight into mechanisms of ion transport across membranes.
短杆菌肽A（一种形成跨膜通道的多肽）与二棕榈酰磷脂酰胆碱（一种磷脂）的复合物的单晶已被制备出来，并通过X射线衍射进行了表征。它们属于空间群P222(1)，晶胞参数为a = 26.8 Å，b = 27.5 Å，c = 32.8 Å。不对称单元似乎是一个由一个短杆菌肽单体和两个磷脂分子组成的复合物。晶胞参数、空间群和化学组成与脂质以双层样基序堆积以及短杆菌肽单体端对端缔合形成功能性二聚体单元是相符的。这些晶体的衍射分辨率达到2 Å，适用于通过单晶X射线分析进行结构研究。这代表了与脂质复合的有序结晶通道的首个实例，其结构的解析可能会为离子跨膜运输机制提供深入见解。
