High-resolution spot-scan electron microscopy of microcrystals of an alpha-helical coiled-coil protein.
J Mol Biol
; 215(1): 161-73, 1990 Sep 05.
Article
en En
| MEDLINE
| ID: mdl-2398496
We describe the electron microscopy of a crystalline assembly of an alpha-helical coiled-coil protein extracted from the ootheca of the praying mantis. Electron diffraction patterns of unstained crystals show crystal lattice sampling of the coiled-coil molecular transform to a resolution beyond 1.5 A. Using a "spot-scan" method of electron imaging, micrographs of unstained crystals have been obtained that visibly diffract laser light from crystal spacings as small as 4.3 A. A projection map was calculated to 4 A using electron diffraction amplitudes and phases from computer-processed images. The projection map clearly shows modulations in density arising from the 5.1 A alpha-helical repeat, the first time this type of modulation has been revealed by electron microscopy. The crystals have p2 plane group symmetry with a = 92.4 A, b = 150.7 A, y = 92.4 degrees. Examination of tilted specimens shows that c is approximately 18 A, indicating that the unit cell is only one molecule thick. A preliminary interpretation shows tightly packed molecules some 400 A long lying with their long axes in the plane of the projection. The molecules have a coiled-coil configuration for most of their length. The possible modes of packing of the molecules in three dimensions are discussed.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Conformación Proteica
/
Proteínas
Límite:
Animals
Idioma:
En
Revista:
J Mol Biol
Año:
1990
Tipo del documento:
Article
Pais de publicación:
Países Bajos