Double-Strand Specific DNase (dsDNase)
Main advantages with dsDNase
- Double-strand DNA specific endonuclease
- High specific activity
- Can be heat-inactivated by moderate heat treatment
- Producing 5′-phospho-oligonucleotide products
Properties
Unit definition: One Unit is defined as an increase in absorbance at 260 nm of 0.001 per minute, using 50 mg/ml high MW DNA in 50 mM Na-acetate pH 5.0 and 5 mM MgCl2 (Kunitz, 1950).
Specific activity: 475 000 Kunitz Units/mg.
pH optimum: pH 7.5 (in Tris-HCl).
Storage buffer: 20 mM Tris-HCl pH 7.5, 2 mM MgCl2, 10 mM NaCl, 0.01% (v/v) Triton X-100, 50% (v/v) glycerol.
Specificity towards double-stranded DNA
Nuclease activity towards double- and single-stranded DNA and RNA oligonucleotides. Assay conditions: 25 mM Tris pH 7.5, 5 mM MgCl2, and 2 μM oligonucleotide. The specificity of dsDNase towards the substrate has been measured using a 15-mer oligonucleotide that is labeled 5′- with FAM and 3′- with DarkQuencher® (Eurogentec). The increase rate in fluorescence over time is directly proportional to enzyme activity.
Relative activities:
| Substrate | Relative activity |
| dsDNA | 100 % |
| ssDNA | < 0.03% |
| dsRNA | < 0.01 % |
| ssRNA | < 0.01 % |
From the data above we can conclude that the dsDNase is double-strand specific.
Heat inactivation
dsDNase can be heat inactivated by heat treatment at 65°C for 15 min. We recommend inactivating the dsDNase in the presence of 1 mM DTT.
Residual activity of dsDNase. 60 Units dsDNase in 200 μl assay buffer was incubated at 65°C. Aliquots were taken out at indicated intervals and residual activity was measured.
Intellectual property
Method for removal of contaminating PCR products from PCR or RT-PCR is subject to patent rights according to US patent 6,541,204 and equivalents. A license for using the patented method is conveyed by purchase of dsDNase from ArcticZymes or its distributors.