Electron microscopy and image analysis of the multicatalytic proteinase |
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Authors: | W Baumeister B Dahlmann R Hegerl F Kopp L Kuehn G Pfeifer |
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Institution: | Max-Planck-Institut für Biochemie, Martinsried, FRG. |
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Abstract: | One electron micrographs, negatively stained multicatalytic proteinase molecules are viewed end-on (ring shaped) or side-on (rectangular shaped). For aurothioglucose, ammonium molybdate- and phosphotungstate-stained molecules, the dimensions measured are consistent. In contrast, uranyl acetate-staining reveals ring-shaped particles which vary in diameter between 12 and 16 nm. This is due to a partial collapse and substantial flattening of the structure. Digital image analysis of side-on views of the particles reveals a tripartite, reel-shaped structure. Within the ring-like, end-on projections of ammonium molybdate-stained molecules six local centres of mass can be discerned; their position appears to depart, however, from a true six-fold symmetry. |
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