Practice question

DNA polymerases vary in fidelity due to presence of 3' to 5' exonuclease domain. Tli polymerase, also called Vent polymerase from Thermococcus litoralis, possesses intrinsic proofreading activity, excising mispaired nucleotides and increasing accuracy approximately 5-10 fold over Taq. Taq from Thermus aquaticus and Tth from Thermus thermophilus lack proofreading, exhibiting higher error rates. For high-fidelity PCR, cloning, mutagenesis, and sequencing applications requiring accurate replication, proofreading enzymes like Tli, Pfu, and Q5 are preferred despite slower extension rates and higher cost.