Description_x000D_ General description_x000D_ Apyrase, also known as ATP-diphosphohydrolase, is expressed in wide variety of plant and animal tissues. The commercially accessible apyrase enzyme is isolated from potato tubers._x000D_ Application_x000D_ Apyrase from potatoes has been used:_x000D_ • to deplete ATP_x000D_ • to degrade endogenous extracellular ATP_x000D_ • as a supplement in acid citrate dextrose solution to treat blood obtained from anesthetized mice_x000D_ 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 ._x000D_ 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)._x000D_ Reaction: ATP → ADP+Pi → AMP+2Pi._x000D_ Packaging_x000D_ 100, 200, 500 units in glass bottle_x000D_ Biochem/physiol Actions_x000D_ Apyrase hydrolyses the phosphoanhydride bonds of nucleoside tri- and di-phosphates in the presence of divalent cations. It has wide substrate specificity for nucleotides. This property of the enzyme makes it suitable for different biotechnical applications, including DNA sequencing and platelet-aggregation inhibition. Apyrase has adenosine 5′-triphosphatase (ATPase) and adenosine 5′-diphosphatase (ADPase) activities._x000D_ 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._x000D_ Packaging_x000D_ Sold on the basis of ATPase units._x000D_ Other Notes_x000D_ This grade has an exceptionally high ATPase/ADPase ratio._x000D_ Unit Definition_x000D_ One unit will liberate 1.0 μmole of inorganic phosphate from ATP or ADP per min at pH 6.5 at 30 °C._x000D_ Physical form_x000D_ Partially purified, lyophilized powder containing potassium succinate buffer salts._x000D_ Preparation Note_x000D_ Derived from white potato