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Free keywords:
Amino Acid Sequence; Animal; Binding Sites; Comparative Study; Cysteine Endopeptidases/ch [Chemistry]; *Cysteine Endopeptidases/me [Metabolism]; Molecular Sequence Data; Molecular Weight; Multienzyme Complexes/ch [Chemistry]; *Multienzyme Complexes/me [Metabolism]; Muscles/en [Enzymology]; Oligopeptides/ch [Chemistry]; Protein Conformation; Rats; Species Specificity; Substrate Specificity; *Thermoplasma/en [Enzymology]
Abstract:
Proteasomes isolated and purified from rat muscle tissue and from the archaebacterium Thermoplasma acidophilum have a very similar size and shape, but the subunit composition is less complex in the archaebacterium as compared to the eukaryotic particle. The archaebacterial enzyme contains a catalytic site with chymotryptic specificity, which is inhibited by serine proteinase inhibitors and clearly differs from the eukaryotic particle which has a minimum of three catalytic sites for peptide bond hydrolysis of a yet undefined mechanism.
