FAQ-818
Have you tested the effect of inhibitors on PCR performance?
Yes. Please see Table 3 in our brochure Maximizing PCR and RT-PCR success. We tested the effects of different inhibitory substances in a number of PCR systems. We also analyzed the effect of including different volumes of reverse transcription (RT) reaction mixtures in PCR. Please see the table below for a list of commonly encountered template impurities and their inhibitory effects on PCR.
Impurities showing inhibitory effects on PCR
| Substance | Inhibitory concentration |
| SDS | >0.005% (w/v) |
| Phenol | >0.2% (v/v) |
| Ethanol | >1% (v/v) |
| Isopropanol | >1% (v/v) |
| Sodium Acetate | ≥5 mM |
| Sodium Chloride | ≥25 nM |
| EDTA | ≥0.5 mM |
| Hemoglobin | ≥1 mg/ml |
| Heparin | ≥0.15 i.U./ml |
| Urea | >20 mM |
| RT reaction mixture | ≥15% |
Related products
Taq PCR Master Mix Kit
PCR Master Mix Kit is a ready-to-use, 2x concentrated solution containing Taq DNA polymerase, dNTPs and MgCl2 at optimal concentrations plus PCR Buffer combining KCl and (NH4)2SO4. Taq PCR Master Mix Kit simplifies workflows by requiring only the addition of template DNA, primers and water. The master mix format reduces pipetting steps, increasing throughput and reproducibility, while reducing the risk of contamination. The buffer formulation further promotes efficiency by reducing or eliminating the need to optimize a PCR by varying annealing temperature or Mg2+ concentration.
PCR Master Mix Kit can be stored at 2–8°C for up to 2 months, allowing even faster PCR setup by eliminating thawing time.
Taq DNA Polymerase
Taq DNA Polymerase is a replicative polymerase derived from the thermophilic eubacterium Thermus aquaticus. Thermostable activity at temperatures above 70°C makes the enzyme suitable for standard and specialized PCR amplification applications. QIAGEN Taq DNA Polymerase is supplied with PCR Buffer specially formulated for fast setup with minimal optimization of PCR parameters, Q-Solution to facilitate amplification of "difficult" (e.g., GC-rich) templates and the additional time-saving advantage of CoralLoad PCR Buffer with two gel-tracking dyes to enable immediate loading of PCR products.
QIAGEN Taq DNA Polymerase is also available in Taq PCR Core Kit that includes dNTPs. If you prefer a Master Mix format, including all needed components, go to Taq PCR Master Mix Kit.
The source of Taq DNA polymerase, the thermophilic eubacterium Thermus aquaticus, was first identified in 1966, living and thriving at about 75°C in the waters of a hot spring in Yellowstone National Park. Taq DNA polymerase has a temperature optimum of 72°C and does not denature at 95°C. This intrinsic thermostability makes Taq DNA polymerase suitable for standard and specialized PCR amplification applications based on its core competence to maintain relatively high catalytic activity and stability after multiple rounds of thermal cycling at high temperatures.
Taq DNA polymerase has 5’→3’ exonuclease activity to remove RNA primers but lacks 3’→5’ exonuclease “proofreading” activity. Many DNA polymerases perform highly accurate DNA synthesis even in the absence of exonucleolytic proofreading. In nature, Thermus aquaticus compensates for the lack of proofreading with a mismatch repair (MMR) system including a MutS homolog that plays a crucial role in correcting replication errors. Taq DNA polymerase performs best when amplifying DNA fragments <2 kb but can amplify longer fragments efficiently under defined reaction conditions — dNTP concentration, pH and the concentration of MgCl2 relative to the total concentration of dNTPs present. Under these conditions, an error rate for Taq DNA polymerase per nucleotide polymerized at 70°C can be achieved as low as 10-5 for base substitution errors and 10-6 for frameshift errors.
The non-template-dependent terminal transferase activity inherent in Taq DNA polymerase and other nonproofreading DNA polymerases provides a highly efficient method to clone PCR products. Taq DNA polymerase adds a single, unpaired residue, preferentially an adenosyl residue, to each 3'-end of a double-stranded amplified product (extra A addition). This property is an advantage for the TA-cloning strategy but may present drawbacks when Taq DNA polymerase is used for microsatellite genotyping analysis.
QIAGEN Taq DNA Polymerase is designed to deliver fast, reliable PCR-related workflows that are easily optimized for efficient amplification performance and reduced error rates.
If you are looking for a DNA polymerase with higher fidelity or longer range than Taq DNA Polymerase, explore our long range or higher fidelity enzymes and mixes. Long range PCR provides highly sensitive and specific long-range amplification for up to 30 kb using any DNA or cDNA template. High fidelity enzymes and master mixes confer higher fidelity, speed and performance compared to standard Taq DNA Polymerase.
QIAGEN Multiplex PCR Kit
The QIAGEN Multiplex PCR Kit is available in a convenient ready-to-use master mix format. The QIAGEN Multiplex PCR Master Mix includes HotStarTaq DNA Polymerase and a unique PCR buffer containing the novel synthetic Factor MP. Together with optimized salt concentrations, this additive stabilizes specifically bound primers and enables efficient extension of all primers in the reaction without the need for optimization. Q-Solution, a novel additive that enables efficient amplification of "difficult" (e.g., GC-rich) templates, is also supplied.
HotStarTaq Master Mix Kit
HotStarTaq Master Mix contains HotStarTaq DNA Polymerase, the unique QIAGEN PCR Buffer that minimizes the requirement for optimization, and dNTPs. Providing all components in a master mix reduces pipetting steps and the risk of contamination, while increasing throughput and reproducibility.
HotStarTaq DNA Polymerase
HotStarTaq DNA Polymerase uses a chemically mediated hot start that, unlike, antibody-mediated systems, leads to complete inactivation of the polymerase until the initial heat activation step at the start of PCR. HotStarTaq DNA Polymerase is supplied with the unique QIAGEN PCR Buffer, which minimizes nonspecific amplification products, primer dimers, and background. Q-Solution, a novel additive that enables efficient amplification of "difficult" (e.g., GC rich) templates, is also provided.