Kinetic mechanism in the absence of metal of Hafnia alvei aspartase in theamination direction

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).