The Tohoku Journal of Experimental Medicine
Online ISSN : 1349-3329
Print ISSN : 0040-8727
ISSN-L : 0040-8727
Regular Contributions
Activation of Mitochondrial ATP-Dependent Protease by Peptides and Proteins
Shoji WatabeMasayuki HaraMisa YamamotoMinoru YoshidaYoshimi YamamotoSusumu Y. Takahashi
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2001 Volume 195 Issue 3 Pages 153-161

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Abstract

We examined the effect of peptides or protein on the proteolytic and ATPase activities of mitochondrial ATP-dependent LON protease purified from bovine adrenal cortex. Peptides/proteins including angiotensin I which stimulated ATPase activity without hydrolysis of any peptide bonds stimulated proteolysis of 125I-labeled substrates at low concentrations; whereas at high concentrations they competitively inhibited proteolysis, thus displaying a biphasic activity profile. All peptides and proteins thus examined stimulated degradation of 125I-labeled substrates. When an ATP analog was substituted for ATP, only inhibition; i.e., no stimulation, of proteolysis by unlabeled peptides was observed. Without activator peptides, degradation of [125I]peptides was higher in the presence of an ATP analog than that in the presence of ATP. ADP, a product of the ATPase reaction, inhibited the proteolytic activity in the absence of an activator peptide but not in its presence. From analogy to E. coli ATP-dependent protease La (LON), we suggest that the activator peptides stimulated the proteolysis by releasing enzyme-bound ADP.

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© 2001 Tohoku University Medical Press
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