DNA modifying enzyme
For in vitro use only!
Unit Definition: One Kunitz unit is defined as the amount of enzyme required to produce an increase in absorbance of 260 nm of 0.001/min/ml at 25°C of highly polymerized DNA. 
Shipping: shipped on gel packs
Storage Conditions: store at -20 °C
avoid freeze/thaw cycles
Shelf Life: 12 months
Concentration: 2 units/μl (Kunitz) 
DNase I is commonly added to cell lysis reagents to remove the viscosity caused by the DNA content in bacterial cell lysates or to remove DNA templates from RNA produced by in vitro transcription.
DNase I removes unwanted DNA from cell lysates to improve protein extraction efficiency.
DNase I (RNase free), Deoxyribonuclease I is a single, glycosylated polypeptide that degrades single- and double-stranded DNA. The enzyme works by cleaving DNA into 5' phosphodinucleotide and small oligonucleotide fragments.
DNase I is used for application requiring the digestion of DNA in which it is crucial to avoid damage to RNA.
DNase I (RNase free)
2 units/μl DNase I in 10 mM Tris-HCl pH 7.5, 10 mM CaCl2, 10 mM MgCl2 and 50 % [v/v] glycerol
DNase I Reaction Buffer
10 x conc. reaction buffer containing 100 mM Tris-HCl pH 7.6 (25°C), 25 mM MgCl2, 5 mM CaCl2
1x DNase I Reaction Buffer
Incubation at 37°C
High levels of monovalent ions such as Na+ and K+ (i.e. 100 mM) may decrease DNase I activity.
DNase I is completely inactivated by incubation at 65 °C for 10 minutes.
> 2500 units/mg protein
 DNase I activity is also measured in 'Degradation Assay units' defined as the amount of enzyme required to completely degrade 1 μg of plasmid DNA in 10 minutes at 37 °C in 10 mM Tris-HCl pH 7.5, 50 mM MgCl2 and 13 mM CaCl2.
1 ‘Degradation Assay unit’ is equivalent to 0.3 ‘Kunitz units’.
Please click the black arrow on the right to expand the citation list. Click publication title for the full text.
Sambrook et al. (1989) Molecular Cloning: A Laboratory Manual, 2nd ed. New York: Cold Spring Harbor Laboratory Press 10.6
Tabor et al. (1997) DNA-Dependent DNA Polymerases. In: Current Protocols in Molecular Biology. Ausubel et al., eds. Wiley & Sons Inc. 3.5.4-6.
Pan et al. (1999) Ca2+- dependent activity of human DNase I and its hyperactive variants. Protein Sci. 8:1780.