Klenow fragment error vs dna pol i11/1/2023 However, in sequence contexts where the error rate is higher, k pol is the same for both correct and mismatched dNTPs, implying that the transition state does not provide additional discrimination against misinsertion. In the sequence context where fidelity is highest, k pol for correct G-dCTP incorporation by Pol ν is ~ 15-fold faster than k pol for G-dTTP misinsertion. The major contributor to sequence-dependent differences in Pol ν error rates is the reaction rate, k pol. ![]() The lower fidelity of Pol ν compared to Klenow fragment can be attributed primarily to a much lower catalytic efficiency for correct dNTP incorporation, whereas both enzymes have similar kinetic parameters for G-dTTP misinsertion. The kinetic data strongly correlate with rates of stable misincorporation during gap-filling DNA synthesis. Here we present a kinetic analysis of this unusual error specificity, in four different sequence contexts and in comparison to Pol ν’s more accurate Family A homologue, the Klenow fragment of E. The latter include Pol ν which, among all A-family polymerases, is uniquely prone to misincorporate dTTP opposite template G in a highly sequence-dependent manner. The fidelity of DNA synthesis by A-family DNA polymerases ranges from very accurate for bacterial, bacteriophage and mitochondrial family members to very low for certain eukaryotic homologues.
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