Different effect of dGTP on 2'-deoxyadenosine metabolism in mitochondria and cytosol

Two enzymes participating in 2'-deoxyadenosine (dAdo) metabolism: dAdo kinase (dAdoK EC 2.7.1.76) and adenosine deaminase (ADA, EC 3.5.4.4) were partially purified from rat liver mitochondria and cytosol and influence of nucleosides and nucleotides on the activity of these enzymes were investigated. Mitochondrial and cytosol dAdoK are separate proteins, while ADA from both subcellular fractions possesses similar physical properties. dGTP, a competitive inhibitor of mitochondrial dAdoK, inhibits cytosol ADA in a mixed way but activates mitochondrial ADA and cytosol dAdoK. A possible effect of dGTP on dAdo metabolism in mitochondria and cytosol is discussed.