Regulatory properties of 14-day embryo and adult hen heart AMP-deaminase; the influence of pH on the enzyme activity.

The variation of kinetic parameters with pH for the reaction catalysed by the purified 14-day embryo and adult hen heart AMP-deaminase was shown to be similar but not identical. The pH-dependence of the half-saturation constant (K0.5) is well pronounced, and the plot of pK0.5 vs pH is manifested as a bell-shaped curve for both developmental forms of the enzyme. In contrast to that, the maximum velocity of the reaction (Vmax) catalyzed by these enzymes does not change significantly in the range pH 5.6-7.4.