The kinetic mechanism of Hafnia alvei aspartase in the amination direction
has been determined in the absence of metal. The initial velocity pattern o
btained by varying the concentration of fumarate at several fixed concentra
tions of NH4+, shows an intersection on the left of the ordinate at pH 7.0,
indicating that the kinetic mechanism is a sequential mechanism in which s
ubstrate inhibition by fumarate is observed. The dead-end inhibition patter
n by varying the concentration of NH4+ at several fixed concentration of su
ccinate shows an intersection on the left of the ordinate. These data are c
onsistent with random addition of NH4+, or fumarate. The Haldane relationsh
ip gives a K-eq of 1.18 x 10(-3) M at pH 7.0, which is in agreement with th
e values obtained from the direct determination of reaction concentrations
at equilibrium (6.0 +/- 0.2 x 10(-3) M).