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Free keywords:
*Cysteine Endopeptidases/ch [Chemistry]; Cysteine Endopeptidases/ul [Ultrastructure]; Microscopy, Electron; *Multienzyme Complexes/ch [Chemistry]; Multienzyme Complexes/ul [Ultrastructure]; Protein Conformation; Support, Non-U.S. Gov't; *Thermoplasma/en [Enzymology]
Abstract:
The three-dimensional structure of proteasomes from the archaebacterium Thermoplasma acidophilum has been determined to a resolution of approximately 2 nm from electron micrographs of negatively stained preparations using the method of 'random conical tilting'. The particles turn out to be essentially cylinder-shaped barrels, 15 nm long and 11 nm wide, enclosing a tripartite inner compartiment. An account is given of some of the present limitations which prevent to attain a higher resolution and possible ways to overcome these limitations are indicated.
