Forst D, Welte W, Wacker T, Diederichs K
Institut für Biophysik und Strahlenbiologie, Albert-Ludwigs-Universität, Freiburg im Breisgau, Germany.
Nat Struct Biol. 1998 Jan;5(1):37-46. doi: 10.1038/nsb0198-37.
The X-ray structure of a sucrose-specific porin (ScrY) from Salmonella typhimurium has been determined by multiple isomorphous replacement at 2.4 A resolution both in its uncomplexed form and with bound sucrose. ScrY is a noncrystallographic trimer of identical subunits, each with 413 structurally well-defined amino acids. A monomer is built up of 18 anti-parallel beta-strands surrounding a hydrophilic pore, with a topology closely similar to that of maltoporin. Two non-overlapping sucrose-binding sites were identified in difference Fourier maps. The higher permeability for sucrose of ScrY as compared to maltoporin is mainly accounted for by differences in their pore-lining residues.
鼠伤寒沙门氏菌蔗糖特异性孔蛋白（ScrY）的X射线结构已通过多同晶置换法在2.4埃分辨率下确定，该结构包括其未结合配体形式以及与蔗糖结合的形式。ScrY是由相同亚基组成的非晶体三聚体，每个亚基有413个结构明确的氨基酸。一个单体由围绕亲水孔的18条反平行β链组成，其拓扑结构与麦芽糖孔蛋白非常相似。在差分傅里叶图中鉴定出两个不重叠的蔗糖结合位点。与麦芽糖孔蛋白相比，ScrY对蔗糖具有更高的通透性，这主要是由它们孔壁残基的差异所致。
