Open AccessATP Synthesis Catalyzed by the ATP Synthase of Escherichia coli Reconstituted into Liposomes
Author(s) -
Fischer Susanne,
Etzold Carsten,
Turina Paola,
DeckersHebestreit Gabriele,
Altendorf Karlheinz,
Gräber Peter
Publication year - 1994
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1994.00167.x
Subject(s) - phosphatidic acid , atp synthase , liposome , escherichia coli , chemistry , phosphatidylcholine , atpase , phosphate , valinomycin , oligomycin , chemiosmosis , catalysis , biochemistry , stereochemistry , nuclear chemistry , membrane , enzyme , phospholipid , gene
The H + ‐translocating F 0 F 1 ‐ATPase from Escherichia coli (EF 0 F 1 ) was purified and reconstituted into preformed reverse‐phase liposomes prepared from egg yolk phosphatidylcholine/phosphatidic acid. The EF 0 F 1 liposomes were energized by an acid/base transition (pH out = 8.3; pH in= 5.0) and a superimposed K + /valinomycin diffusion potential ([K + ] out = 100 mM; [K + ] in = 0.6 mM) yielding a maximum rate (turnover number) of ATP synthesis of 27±8 mol ATP · molEF 0 F 1 −1 · s −1 ), i.e. 27±8 s −1 This reaction was inhibited by NH 4 Cl or by addition of the F 0 F 1 , inhibitor N,N′ ‐dicyclohexylcarbodiimide. The rate of ATP synthesis measured as a function of the phosphate and ADP concentrations, can be described by Michaelis‐Menten kinetics with a K m of 0.7±0.2 mM for phosphate ([ADP] = 200 μM) and a K m , of 27±7 μM for ADP ([phosphate] = 5 mM), respectively.