Cleaves A-5'-PPP-5'A to yield AMP and ADP. Can cleave all dinucleoside polyphosphates, provided the phosphate chain contains at least 3 phosphates and that 1 of the 2 bases composing the nucleotide is a purine. Is most effective on dinucleoside triphosphates. Negatively regulates intracellular dinucleoside polyphosphate levels, which elevate following heat shock (By similarity). H2O + P(1),P(3)-bis(5'-adenosyl) triphosphate = ADP + AMP + 2 H(+) Divalent metal cations. Mn(2+) is the preferred ion. Homodimer.