Study of ATP Diphosphohydrolases in porcine kidney and liver

Abstract

In the last few years, the number of reports on extracellular nucleotides and nucleosides has increased markedly. Some of these focus on the metabolism of extracellular purine and pyrimidine nucleotides, while others deal with the interaction of nucleotides with their specific receptors at the cell surface. Biological responses to extracellular ATP and adenosine have been documented in virtually every major organ and/or tissue system studied so far. These effects are mediated via P 1 or P2 purinoceptors on the cell surface. The extracellular breakdown of nucleotides involves several ectoenzymes, commonly named ectonucleotidases. Most of these enzymes are intrinsic proteins of the plasma membrane, with their catalytic site oriented towards the extracellular space). Thus, ectonucleotidases regulate extracellular concentrations of nucleotides and nucleosides. Our study focuses on one of these ectonucleotidases, the ATP diphosphohydrolase (ATPDase or apyrase, E.C. 3 .6.1.5). This enzyme hydrolyzes the y- and/or ~phosphate of all naturally occurring nucleoside tri- and diphosphates and has been extensively studied and characterized in many tissues.