Crystal structure of cyclo(Pro-Gly)3:Li complex: a model for ion transport by cyclo(Pro-Gly)3.
Crystal structure of cyclo(Pro-Gly)3:Li complex: a model for ion transport by cyclo(Pro-Gly)3.
复制标题
环(Pro-Gly)3:Li复合物的晶体结构：环(Pro-Gly)3的离子传输模型。
DOI：
10.1002/bip.360340804
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发表时间：
1994
期刊：
影响因子：
2.9
通讯作者：
Bhandary,KK
中科院分区：
文献类型：
--
作者：
Thomas,LM;Ramasubbu,N;Bhandary,KK
用x射线衍射分析了环（Pro‐Gly）3（PG3）与LiSCN （C22H30N7O6SLi）配合物的晶体结构。晶体在六边形环境中属于空间群R3，晶胞参数为a= 12.581(1),c= 29.705(3) Å，V= 4072.0 Å3，Z= 6,Mr= 527.53,Dc= 1.23 g/cm3。使用SHELXS‐86程序直接求解晶体结构，并将1645个反射（I> 2σI）的r值细化为5.3%。晶体结构中有两种构象。一个构象在肽平面的一边有三个羰基另一边也有三个。另一个构象的6个羰基都在肽平面的同一侧。这两种构象都独立地与一个Li离子结合。基于Li配合物的构象和其他报道的PG3形成的离子配合物，我们提出了一个离子在脂质膜上运输的模型。该模型的特点如下：(1)PG3在与金属离子络合和运输时，在脂质双分子层中形成六聚体堆叠。(2)为了使离子沿通道传递，它经历了构象翻转。参与PG3分子翻转的构象变化所需的能量可以由离子传输过程中的外加电位提供。©1994 John Wiley & Sons, Inc
The crystal structure of cyclo(Pro‐Gly)3(PG3) complex with LiSCN (C22H30N7O6SLi) has been solved by x‐ray diffraction. The crystals belong to the space group R3 in the hexagonal setting with unit cell parameters ofa= 12.581(1),c= 29.705(3) Å,V= 4072.0 Å3,Z= 6,Mr= 527.53,Dc= 1.23 g/cm3. The crystal structure was solved by direct methods using the program SHELXS‐86 and refined to anRvalue of 5.3% for 1645 reflections (I> 2σI). There are two conformers in the crystal structure. One conformer has three carbonyls on one side and three on the other side of the peptide plane. The other conformer has all six of the carbonyls on the same side of the peptide plane. Both of these conformers bind independently to a Li ion. Based on the conformers of the Li complex and other reported ion complexes formed by PG3, we propose a model for the transport of ions across the lipid membrane. The features of the model are as follows: (1) PG3 forms a hexameric stack in a lipid bilayer when complexing and transporting metal ions. (2) It undergoes a conformational flipping in order pass the ion along the channel. The energy required for the conformational change involved in the flipping of the PG3 molecule may be provided by the applied potential during ion transport. © 1994 John Wiley & Sons, Inc.