Affiliation:
1. Consejo Superior Investigaciones Científicas, Membrane Biochemistry Unit, Velázquez, 144, Madrid-6, Spain
Abstract
The action of atebrin on purified adenosine triphosphatase (ATPase) from
Micrococcus lysodeikticus
was studied as well as on the membrane-bound and soluble ATPases from
Escherichia coli
and
Bacillus megaterium
. Atebrin inhibited the Ca
2+
-dependent activity of all these enzymes, and the inhibition was reversed by an excess of Ca
2+
ions. Kinetic studies carried out with the purified enzyme from
M. lysodeikticus
showed that the inhibition by atebrin was strongly cooperative, suggesting the complex nature of the process. On the other hand, atebrin stimulated the Mg
2+
ATPase activity of the
M. lysodeikticus
enzyme, displacing its adenosine 5′-triphosphate (ATP)/Mg
2+
optimum ratios, but inhibited the Mg
2+
-ATPase activity of
E. coli
provided that ATP was in excess over Mg
2+
, i.e., that the ATP/Mg
2+
ratio was higher than its optimum. These results suggest that divalent cations influence the bacterial ATPases in different ways depending on the type of divalent ion and/or enzyme. The effect of atebrin on bacterial ATPases may reflect those differences, and its complex mechanism of action might be related to the existence of more than one site for divalent cations and/or distinct conformational states in these enzymes.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology
Cited by
1 articles.
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