Analysis of time-dependent change of Escherichia coli F1-ATPase activity and its relationship with apparent negative cooperativity.
Except for the case of gradual activation of EF1 (F1-ATPase from Escherichia coli) caused by the dissociation of the epsilon subunit [Laget, P. P. and Smith, J. B. (1979) Arch. Biochem. Biophys. 197, 83-89], EF1 has long been thought not to show a time-dependent change in activity [Senior, A.E. et al. (1992) Arch. Biochem. Biophys. 297, 340-344]. Here, we report the time-dependent inactivation and activation of EF1, which are apparently similar to those of mitochondrial F1-ATPases [Vasilyeva, E.A. et al. (1982) Biochem. J. 202, 15-23]. Analysis of these changes as a function of ATP concentrations in relation to negative cooperativity revealed that the initial inactivation phase was attributable to the decrease in the Vmax associated with the low Km (around 10 microM), and the following activation, probably due to the dissociation of the epsilon subunit, corresponded to the increase in the Vmax associated with the high Km (in the order of 100 microM). Thus, the time-dependent change in EF1 activity is closely related to the apparent negative cooperativity (multiple Km values) of ATP hydrolysis.
Kato
Y
Y
Research Laboratory of Resources Utilization, Tokyo Institute of Technology, Kanagawa, Japan.
Sasayama
T
T
Muneyuki
E
E
Yoshida
M
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology*; D006868:Hydrolysis; D007700:Kinetics; D006180:Proton-Translocating ATPases / Q000378:metabolism*
D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases