A time lag was observed during the amination reaction of Hafnia alvei aspartase. The time lag was shortened at lower pH, but lengthened at higher pH. Also, the time lag was shortened at higher temperature, lengthened at lower temperature. L-aspartate, D-aspartate and α-methyl-DL-aspartate markedly revealed the activating effects. The time lag and the nonlinear kinetics were eliminated when one of these effectors was added in the reaction mixture. These results suggest that these effectors occupy a distant allosteric activator site apart from active site.