Patent ID: 7211414

Claim:
A method for using modified nucleotides to alter base incorporation fidelity comprising the step of adding a modified nucleotide including a molecular tag to a nucleotide polymerization medium comprising a nucleotide polymerizing agent, a primer, a template, and a pyrophosphorolysis inhibitor selected from the group consisting of compounds of the following general formulas and mixtures or combinations thereof: Z-OPO 2 O-Z′ (a) Z-PO 2 O-Z′ (b) Z-OPO 2 -Z′ (c) Z-PO 2 -Z′ (d) Z-OPO 2 —(OP(EE′)O) n —PO 2 O-Z′ (e) Z-OPO 2 —(OP(EE′)O) n PO 2 -Z′ (f) Z-PO 2 —(OP(EE′)O) n PO 2 O-Z′ (g) Z-PO 2 —(OP(EE′)O) n PO 2 -Z′ (h) where Z or Z′ is a hydrogen atom or a thermally stable substituent comprising primarily one or more atoms selected from the group carbon, nitrogen, oxygen, sulfur and phosphorus with sufficient hydrogen atoms to satisfy valence requirements, E and E′ are an oxygen atom or a thermally stable substituent comprising primarily one or more atoms selected from the group carbon, nitrogen, oxygen, sulfur and phosphorus with sufficient hydrogen atoms to satisfy valence requirements and n is an integer having a value between 0 and about 5, where the modified nucleotide increases base incorporation fidelity of the nucleotide polymerizing agent relative to a base incorporation fidelity of the nucleotide polymerizing agent in the absence of the modified nucleotide to produce an extended primer having reduced incorrect base incorporations and where the pyrophosphorolysis inhibits pryosphosphorolysis reduces the amount of pyrophosphorolysis occurring in the reaction.