GroEL-like particles of Thermus aquaticus are homo-oligomeric complexes of two stacked seven member rings, sedimenting in the gradient at 20S. The apparent molecular mass of the native particles is 820,000 (+/- 30,000). The protein complex is composed with one polypeptide of M(r) 59,000. Immunoblotting results and N-terminal amino acid analysis indicate that the complex is significantly related to the chaperonins. No proteolytic activity was identified in the purified GroEL-like particles. In the presence of Mg2+ and K+ the complex exhibits temperature dependent ATPase activity. Under optimum temperature (75 degrees C) GroEL is stable and hydrolyze ATP with a specific activity of 0.47 mumol min-1 mg-1.

Institute of Microbiology Academy of Sciences of the Czech Republic Prague

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