Transphosphorylation of Adenosine Di- and Tri-phosphates in the Presence of Calcium Phosphate Precipitates

IT has been discovered by Lowenstein 1,2 that in dilute aqueous solution in the presence of certain divalent cations there is a tendency for the terminal phosphate group of the adenosine triphosphate ion (ATP) to be transferred to inorganic phosphate or other suitable acceptor. For example: where ADP represents the adenosine diphosphate ion. Krane and Glimcher 3 have recently shown that a similar non-enzymatic transphosphorylation occurs on the surface of calcium phosphate crystals with hydroxyapatite structure when they are in contact with aqueous solutions of ATP. In this reaction the acceptor is phosphate belonging to the crystal. The rate of reaction is faster and less dependent on p H than that of Lowenstein.