کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
2829046 | 1162782 | 2008 | 9 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Helical structure of unidirectionally shadowed metal replicas of cyanide hydratase from Gloeocercospora sorghi Helical structure of unidirectionally shadowed metal replicas of cyanide hydratase from Gloeocercospora sorghi](/preview/png/2829046.png)
The helical filaments of the cyanide hydratase from Gloeocercospora sorghi have been reconstructed in three dimensions from freeze dried, unidirectionally shadowed specimens using iterative real-space helical reconstruction. The average power spectrum of all selected images has three clear reflections on different layer lines. The reconstruction is complicated by the fact that three possible indexing schemes are possible and reconstructions using the starting symmetries based on each of these indexing schemes converge on three-dimensional volumes which appear plausible. Because only one side is visible in shadowed specimens, it is necessary to examine the phases from a single filament by cryo-electron microscopy in order to make an unequivocal assignment of the symmetry. Because of the novel nature of the reconstruction method used here, conventional cryo-EM methods were also used to determine a second reconstruction, allowing us to make comparisons between the two. The filament is shown to have a left-handed one-start helix with D1 symmetry, 5.46 dimers per turn and a pitch of 7.15 nm. The reconstruction suggests the presence of an interaction across the groove not previously seen in nitrilase helical fibres.
Journal: Journal of Structural Biology - Volume 161, Issue 2, February 2008, Pages 111–119