Verdaguer N, Fita I, Subirana J A
Unidad de Química Macromolecular Escuela T. S. de Ingenieros Industriales, Barcelona, Spain.
Int J Biol Macromol. 1990 Oct;12(5):315-20. doi: 10.1016/0141-8130(90)90021-2.
The structure of the tripeptide L-lysyl-L-tyrosyl-L-serine acetate was determined by X-ray diffraction. The crystals are triclinic space group P1, with two peptide molecules in the unit cell. The peptides are in zwitterionic form with positive charges both in the amino terminal and epsilon-amino groups of lysine. A negative charge is found in one of the carboxylic groups, whereas the other one is protonated. Both peptides show very similar backbone torsional angles, in the beta pleated sheet region, but different tyrosine and serine side-chain conformations. The two lysine side chains have a similar conformation g + tg + t, which had not been previously found. In the unit cell we also find one water molecule, one isopropanol molecule and four acetic acid molecules, three of them likely to be present as acetate anions. These molecules form layers which separate the beta-pleated sheets. The whole structure looks like an ordered solution of peptides in the beta-sheet conformation. An extensive network of hydrogen bonds stabilizes the crystal structure.
通过X射线衍射确定了三肽L-赖氨酰-L-酪氨酰-L-丝氨酸乙酸盐的结构。晶体属于三斜晶系空间群P1，晶胞中有两个肽分子。肽呈两性离子形式，赖氨酸的氨基末端和ε-氨基均带正电荷。在一个羧基中发现一个负电荷，而另一个羧基则被质子化。两种肽在β折叠片层区域显示出非常相似的主链扭转角，但酪氨酸和丝氨酸侧链构象不同。两条赖氨酸侧链具有相似的构象g + tg + t，这是以前未曾发现的。在晶胞中我们还发现一个水分子、一个异丙醇分子和四个乙酸分子，其中三个可能以乙酸根阴离子的形式存在。这些分子形成层，将β折叠片层分隔开。整个结构看起来像β片层构象的肽的有序溶液。广泛的氢键网络稳定了晶体结构。
