Merck, SRE0019-500UN, Apyrase from potatoes

Application
At least two isoenzymes are found in different varieties of S. tuberosum: one with a high ATPase/ADPase ratio (∼10) and another with a low ratio (∼1).
Reaction: ATP → ADP+Pi → AMP+2Pi.
Apyrase is used to hydrolyze nucleoside triphosphates and diphosphates. For hydrolysis of organic di and triphosphates, the optimal pH is 6, and for inorganic substrates, the optimal pH is 5.1. Apyrase, from Sigma, has been used in inhibition studies of platelet-aggregation.
Biochem/physiol Actions
Apyrase is found in all eukaryotes and some prokaryotes. Apyrase, from potato, has a crucial role in regulating growth and development. Apyrase is involved in the inactivation of synaptic ATP as a neurotransmitter following nerve stimulation and in the inhibition of ADP induced platelet aggregation to prevent thrombosis. Divalent metal ions are required for activity and best activity is observed with calcium ion at 5 mM.
Physical form
Partially purified, lyophilized powder containing potassium succinate buffer salts.
Preparation Note
Sold on the basis of ATPase units.
Other Notes
One unit will liberate 1.0 μmole of inorganic phosphate from ATP or ADP per min at pH 6.5 at 30 °C.
This grade has a low ATPase/ADPase ratio.