Stoffel DNA Polymerase (1000 U)

From QIAGEN, this recombinant enzyme is a 62.7 kDa fragment of thermostable Taq DNA polymerase isolated from Thermus aquaticus and expressed in an Escherichia coli host. The modified gene encodes a 540 amino acid fragment lacking the N-terminal 292 amino acid portion of the full-length enzyme. It is described as a universal and easy-to-use DNA polymerase that works rapidly and effectively in various PCR conditions.

It is recommended for a wide range of applications that require DNA synthesis in extremely high temperatures, including GC-rich and secondary-structure templates, and supports the simultaneous amplification of multiple targets in the same reaction. The hybridization probes used in LightCycler assays must not be hydrolysed, so accuracy of quantitative measurements is improved using the Stoffel Fragment that lacks endonucleolytic activity. The enzyme catalyses DNA synthesis in a 5' → 3' direction and does not exhibit 3' → 5' or 5' → 3' exonuclease activity. Its thermostability is about twice as high as that of TaqNova DNA Polymerase, with slightly greater fidelity than full-length Taq, allowing denaturation temperatures as high as 98°C. A broad MgCl₂ optimum range of 2.5–5 mM is reported, with a 3 mM MgCl₂ concentration suggested as a starting point for PCR protocol optimisation. One unit is defined as the amount of enzyme required to incorporate 10 nmol of dNTPs into an insoluble DNA fraction in 30 minutes at 72°C in a 50 μL reaction.

The enzyme is supplied in 20 mM Tris-HCl (pH 8.0 at 25°C), 100 mM KCl, 0.1 mM EDTA, 1 mM DTT, 0.5% (v/v) Nonidet P40, 0.5% (v/v) Tween 20, and 50% (v/v) glycerol. The product must be shipped on dry ice and stored at –20°C. Quality control includes evaluation of DNase contamination through extensive PCR reactions.