Nat Biotechnol. 2004 Jun;22(6):755-9 doi:10.1038/nbt974

Ghadessy FJ, Ramsay N, Boudsocq F, Loakes D, Brown A, Iwai S, Vaisman A, Woodgate R, Holliger P.

Generic expansion of the substrate spectrum of a DNA polymerase by directed evolution.

Polymerases selected on the ability to amplify their gene despite a 3' mismach in the primers were shown to be able to incorporate a broad range of nucleotide analogs.