S. Fischer et al., ATP SYNTHESIS CATALYZED BY THE ATP SYNTHASE OF ESCHERICHIA-COLI RECONSTITUTED INTO LIPOSOMES, European journal of biochemistry, 225(1), 1994, pp. 167-172
The H+-translocating F0F1 ATPase from Escherichia coli (EF(0)F(1)) was
purified and reconstituted into preformed reverse-phase liposomes pre
pared 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.mol EF(0)F(1)(-1).s(-l))
, i.e. 27 +/- 8 s(-l). This reaction was inhibited by NH4Cl or by addi
tion of the F0F1 inhibitor N,N'-dicyclohexylcarbodiimide. The rate of
ATP synthesis measured as a function of the phosphate and ADP concentr
ations, can be described by Michaelis-Menten kinetics with a K-m of 0.
7 +/- 0.2 mM for phosphate([ADP] = 200 mu M) and a K, of 27 +/- 7 mu M
for ADP ([phosphate] = 5 mM), respectively.