DNase I

We do not test for protease activity as part of our QC but there is PMSF (a protease inhibitor) in the storage buffer. Furthermore, in the preparation of DNase I, we use a soybean trypsin inhibitor column to remove proteases.

The Amplification Grade DNase I (Cat. No. 18068-015) is subjected to an extra final HPLC purification step to remove traces of RNases. The Amplification Grade DNase I is supplied as 1 unit/µL and comes with 10X buffer (200 mM Tris-HCL pH 8.4, 20 mM MgCl2, 500 mM KCl) and a vial of 25mM EDTA.

In RT-PCR, a large excess of Amplification Grade DNase I could be used to digest an RNA template without degradation of the RNA (in-house data). Use Amplification Grade DNase I to remove genomic DNA carryover in RNA samples prior to RT-PCR.

The regular DNase I is supplied at 5-15 mg/mL (50-375 U/µL) and does not come with its own buffer.

Add of 1 µL of 25 mM EDTA solution to the reaction mixture in 10 µL reaction with 1 unit DNase I, Amplification Grade (or 1:1 molar ratio of Mg++ ions:EDTA) to chelate the Mg++ ions in the DNase I buffer. Heat for 10 min at 65 degrees C.

Note: It is vital that the EDTA be at least at 2 mM prior to heat-inactivation to avoid Mg-dependent RNA hydrolysis.

DNA-free and Turbo-free versions of DNase I can be inactivated with included DNase Inactivation Reagent.

Specific activities vary by lot. Our DNase I must have a specific activity greater than 10,000 units/mg to pass our quality standards. Average specific activities vary between 10,000-25,000 units/mg.

Most of our DNase I products are guaranteed free of RNase activity. However, please note that Cat. No. 18047-019 is not tested for RNAse and is recommended primarily for protein applications. The other products are suitable for removing DNA from both RNA and protein preparations, for nick translating DNA, and for generating random fragments of DNA. For more demanding RT-PCR applications, we recommend using DNAse I, Amplification Grade.