Semi-Quantitative Characterization of NH₄⁺ and K⁺-Mediated Inhibition of Pyrobaculum calidifontis DNA Polymerase Using Endpoint PCR

This study provides a semi-quantitative analysis of monovalent cation-mediated inhibition of recombinant Pyrobaculum calidifontis (Pca) DNA polymerase. Using endpoint PCR and densitometric analysis, the research determines that K+ is a significantly more potent inhibitor (IC50 = 4.74 mM) compared to NH4+ (IC50 = 32.90 mM). A critical inhibitory threshold was identified in the 20-30 mM range for both ions. These findings offer a framework for optimizing PCR buffer conditions for high-fidelity archaeal polymerases.