  Kinetic theory and thermodynamics are applied to DNA polymerases with
exonuclease activity, taking into account the dependence of the rates on the
previously incorportated nucleotide. The replication fidelity is shown to
increase significantly thanks to this dependence at the basis of the mechanism
of exonuclease proofreading. In particular, this dependence can provide up to a
hundred-fold lowering of the error probability under physiological conditions.
Theory is compared with numerical simulations for the DNA polymerases of T7
viruses and human mitochondria.
