The Escherichia coli F1F0 ATP synthase displays biphasic synthesis kinetics.
The F1F0 proton-translocating ATPase/synthase is the primary generator of ATP in most organisms growing aerobically. Kinetic assays of ATP synthesis have been conducted using enzymes from mitochondria and chloroplasts. However, limited data on ATP synthesis by the model Escherichia coli enzyme are available, mostly because of the lack of an efficient and reproducible assay. We have developed an optimized assay and have collected synthase kinetic data over a substrate concentration range of 2 orders of magnitude for both ADP and Pi from the synthase enzyme of E. coli. Negative and positive cooperativity of substrate binding and positive catalytic cooperativity were all observed. ATP synthesis displayed biphasic kinetics for ADP indicating that 1) the enzyme is capable of catalyzing efficient ATP synthesis when only two of three catalytic sites are occupied by ADP; and 2) occupation of the third site further activates the rate of catalysis.
Tomashek
John J
JJ
Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
Glagoleva
Olga B
OB
Brusilow
William S A
WS
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000096:biosynthesis*; D025243:Bacterial Proton-Translocating ATPases / Q000737:chemistry / Q000378:metabolism*; D020134:Catalytic Domain; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D010710:Phosphates / Q000378:metabolism
D010710:Phosphates; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D025243:Bacterial Proton-Translocating ATPases