JBC, Vol. 251, Issue 11, 3457-3462, Jun, 1976
Regulation of glutaminase B in Escherichia coli. II. Modulaltion of activity by carbosylate and borate ions
S. Prusiner and E. R. Stadtman
Glutaminase B is both activated and inhibited by L-glutamate, the product
of the reaction. The activation process is time- and temperature-dependent.
Activation by L-glutamate alters the Vmax, So.5, and shape of the substrate
saturation curve. The activation decays as a first order process with time
after separation of L-glutamate from glutaminase B. L-Glutamate inhibits
both glutaminase B and the glutamate-activated enzyme. Like L-glutamate,
borate activates and inhibits glutaminase B. Inhibition of the enzyme by
glutamine and glutamate analogs is also examined and similarities between
the glutamate activation and activation by warming at 23 degrees are noted.