How do I determine optimal DNA polymerase concentration for PCR?
Many thermostable DNA polymerases are now commercially available, each with different characteristics of thermal stability, exonuclease activity, processivity, fidelity and reverse transcriptase activity. Taq DNA polymerase, with its heat stability, high optimal temperature and broad pH tolerance, is the most widely used thermostable DNA polymerase. The recommended concentration range for Taq DNA polymerase is between 1 and 2.5 units per 100 l reaction. Enzyme requirements may vary with respect to individual target templates, primers and suppliers. Taq DNA polymerase from different suppliers my behave differently because of different formulations, assay conditions and unit definitions (especially for non-licensed products). If the enzyme concentration is too high (>4 units/ml), non-specific background products may accumulate. If it is too low, an insufficient amount of desired product is made. Click here to learn more about PCR 1.
