Protocol
General precautions should be taken when setting up a PCR, including setting up the reaction on ice, adding polymerase last, gentle pipetting, thorough mixing and a quick centrifugation. The following procedure can be used as a guideline. Reactions may need to be optimized individually.
Reaction setup (for 50 µl)
| Component |
Volume (µl) |
Final concentration |
| Sterile H2O |
Variable |
|
| 5x VeraSeq Buffer II or 5x VeraSeq GC Buffer |
10 |
1x |
| 10 mM dNTP mix |
1 |
200 µM each |
| Primer 1 |
Variable |
0.2 µM |
| Primer 2 |
Variable |
0.2 µM |
| DNA template |
Variable |
See note 4 |
| VeraSeq 2.0 DNA Polymerase |
0.5 |
1 U |
Total reaction volume can be adjusted as needed.
Typical cycling conditions
| Step |
Temperature |
Time |
Cycles |
| Initial denaturation |
98°C |
30 seconds |
1 |
Denaturation Annealing Extension |
98°C Varies 72°C |
5–10 seconds 10–30 seconds 15–30 seconds/kb |
15–35 |
| Final extension |
72°C 4°C |
5–10 mininutes hold |
1 |
| Cycling conditions may need to be optimized, depending on the amplicon of interest |
Notes:
5x VeraSeq Buffer II should be used as the default buffer for high-fidelity amplification. For GC-rich and difficult templates, use 5x VeraSeq GC Buffer. VeraSeq 2.0 High-Fidelity DNA Polymerase stalls on uracil residues in the template strand and prevents further extension. Therefore, dUTP should not be used in the reaction. If DNA templates contains uracil or dUTP needs to be incorporated, use VeraSeq ULtra (P7520L). A final concentration of 0.2 µM is recommended for each primer, but it can be varied in the range of 0.2–1µM.
Recommended template quantities:
| Complexity |
Source example |
Guideline |
| Low |
Plasmid, virus, BAC |
1 pg – 10 ng |
| High |
Genomic DNA |
50–250 ng |
One unit is usually sufficient for amplifying most targets. For long targets (>1kb), difficult templates or to increase yield, it may be necessary to add up to 2 units of enzyme. Both 5x VeraSeq Buffer II and GC buffer are formulated to provide a final 1x concentration of MgCl2 of 1.5mM. In cases where additional Mg2+ is required, adjust the final Mg2+ concentration in 0.2mM steps.
For GC rich templates, DMSO may be used to reduce the secondary structure of complex templates. DMSO is generally used at a 3% final concentration (v/v). If additional optimization is required, adjust the concentration in 1–2% increments (2–9% in final reaction). The primer annealing temperature should be lowered to account for the presence of the solvent. VeraSeq 2.0 High-Fidelity DNA Polymerase is also compatible with other PCR-enhancing additives, such as BSA and betaine.
Quality control analysis
Specific activity was measured using a twofold serial dilution method. Dilutions of enzyme were made in 1x reaction buffer and added to 50 µl reactions containing activated calf thymus DNA; 25 mM TAPS (tris-[hydroxymethyl]-methyl-amino-propanesulfonic acid, sodium salt), pH 9.3 at 25°C; 50 mM KCl; 2 mM MgCl2; 1 mM β-mercaptoethanol; 200 µM each dATP, dGTP, dTTP; and 100 µM [3H]-dCTP (0.075 Ci/mmole). Reaction vessels were mixed and incubated at 74°C for 10 minutes.
Protein concentration is determined by OD280 absorbance.
Physical purity is evaluated by SDS-PAGE of concentrated and diluted enzyme solutions followed by silver-stain detection. Purity is assessed by comparing the aggregate mass of contaminant bands in the concentrated sample to the mass of the band corresponding to the protein of interest in the diluted sample.
Double-stranded endonuclease activity is determined in a 50 µl reaction containing 0.5 µg of plasmid DNA and 10 µl of enzyme solution incubated for 4 hours at 37°C.
E. coli contamination is evaluated using 5 µl replicate samples of enzyme solution that are denatured and screened in a TaqMan qPCR assay for the presence of contaminating E. coli genomic DNA using oligonucleotide primers corresponding to the 16S rRNA locus.