This invention discloses methods for detecting specific nucleic acid sequences, interrogating the identity of a specific base within a sequence, and assaying endonuclease and exonuclease activity. DNA or RNA probes are hybridized to target nucleic acid sequences. Probes that are complementary to the target sequence at each base are depolymerized, while probes which differ from the target at the interrogation position are not depolymerized. The nucleic acid detection systems utilize the pyrophosphorolysis reaction catalyzed by various polymerases to produce deoxyribonucleoside triphosphates or ribonucleoside triphosphates. dNTPs are transformed to ATP by the action of NDPK. The ATP produced by these reactions is detected by luciferase or NADH based detection systems.
