JBC, Vol. 253, Issue 12, 4292-4296, Jun, 1978
Kinetic studies on bacterial plasma membrane ATPase (F1). Nucleotide-induced long term inactivation of ATP hydrolyzing activity is linked to the formation of multiple "tight" enzyme nucleotide complexes
M. Hockel, F. W. Hulla, S. Risi and K. Dose
ADP and the ATP analogs Nb-S6ITP
(6-[(3-carboxy-4-nitrophenyl)thio]-9-beta-D-ribofuranosylpurine
5'-triphosphate) and AMP-P(NH)P (adenyl-5'-yl imidodiphosphate) interact
with soluble plasma membrane ATPase (F1) from Micrococcus species in two
ways: (i) at short incubation times, these inhibitors exhibit the kinetics
of competitive inhibition, (ii) at long incubation times, these inhibitors
induce an inactivation of the ATPase which can be reversed only in the case
of AMP-P(NH)P. Kinetic treatment of the long term inactivation by ADP or
Nb-S6ITP reveals a pseudo-first order process via the formation of an
enzyme-inhibitor complex for which a Km analogous constant is obtained that
is identical with the corresponding Ki value of the competitive inhibition.
The long term inactivation by ADP and Nb-S6ITP involves the successive
"tight" binding of 6 +/- 1 nucleotides/F1 molecule. One additional ADP
molecule/F1 complex which is also "tightly" bound has no effect on the
ATPase activity. The long term inactivation by ADP and Nb-S6ITP is
inhibited at higher inhibitor concentrations according to a kinetics
analogous to a substrate excess inhibition. Evidence is presented
indicating that the mechanism of ATP hydrolysis by F1 and the long term
inactivation by ADP or Nb-S6ITP are related processes. The mechanism of
long term inactivation by AMP-P(NH)P appears to be different from that of
ADP or Nb-S6ITP.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
