[Fidelity of a polymerization reaction according to the proximity to equilibrium]

Pyrophosphorolysis, the reverse reaction of nucleotide polymerisation during replication or transcription must influence error-rates. Calculations suggest, for a wide range of reaction mechanisms, a linear dependency between pyrophosphate concentration and the ratio correct/incorrect substrate incorporation. Errors in A.T -rich regions should be particularly sensitive to changes in pyrophosphate concentration.