ISSN:
1432-072X
Keywords:
Motile Streptococcus
;
Membrane-bound ATPase
;
DCCD
;
Valinomycin
;
Uncouplers
;
Protonmotive force
;
ATP synthesis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract ATPase was detected in the membranes of a motile Streptococcus. Maximal enzymic activity was observed at pH 8 and ATP/Mg2+ ratio of 2. Mn2+ and Ca2+ could replace Mg2+ to some extent. Besides ATP, GTP and ITP were substrates. The enzyme was inhibited by N,N′-dicyclohexylcarbodiimide but not by sodium azide, uncouplers or bathophenanthroline. An electrochemical gradient of protons, which was artificially imposed across the membranes of Streptococcus cells by manipulation of either the K+ diffusion potential or the transmembrane pH gradient, led to ATP synthesis. ATP synthesis was abolished by proton conductors, an inhibitor of the ATPase or an increase in the extracellular K+ concentration. A comparison between the phosphate potential and the electrochemical proton gradient showed that the data found are in agreement with a stoichiometry of 2 protons translocated per molecule ATP synthesized.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00407924
Permalink
