In addition to polymerase activity, this DNA polymerase exhibits 3' to 5' exonuclease activity. Intein encoded endonucleases are thought to mediate intein mobility by site-specific recombination initiated by endonuclease cleavage at the 'homing site' in gene that lack the intein (Probable). Intein splicing has been shown to occur via a branched intermediate that is resolved as the reaction proceeds; formation of the branched intermediate is reversible in response to pH shifts (PubMed:8269515). a 2'-deoxyribonucleoside 5'-triphosphate + DNA(n) = diphosphate + DNA(n+1) Optimum pH for intein splicing is 4.5-6.5. This protein undergoes a protein self splicing that involves a post-translational excision of the intervening region (intein) followed by peptide ligation. Used in the PCR method because of its high thermostability and low error rate. Sold by New England Biolabs. Belongs to the DNA polymerase type-B family.