Purification and properties of AMP-deaminase from human uterine smooth muscle

AMP-deaminase from human uterine smooth muscle has been isolated, and properties of the enzyme were characterized. At pH 7.0, and in the presence of 100 mM potassium chloride the enzyme manifests a distinctly sigmoidal type of kinetics, with S0.5 parameter value about 12 mM. 1 mM ATP strongly activates the enzyme, and diminishes the value of S0.5 to 1.2 mM. In contrast to that 2.5 mM orthophosphate slightly inhibits the activity of AMP-deaminase studied and increases the S0.5 to about 14 mM. Similarly to ATP, orthophosphate does not influence the maximum velocity of the reaction. Electrophoresis in the presence of sodium dodecyl sulphate revealed that the molecular weight of human smooth muscle AMP-deaminase subunit is close to 37 kDa.