1 unit causes an increase in absorbance at 260nm of 0.0001 per minute per ml at 25oC when acting upon highly polymerized DNA at pH 5.0.
Note: As measured at GenDEPOT, one Kunitz unit digests 1ug of lambda DNA in 10 minutes at 37oC in 50mM Tris, 1mM Mg2+, 1mM Ca2+, pH 7.8 in a 50ul reaction. Correlation of digestion units with Kunitz units is different for other DNA and buffer systems.
DNase I (Deoxyribonuclease I ) is a dialyzed lyophilized powder from bovine pancrease that has been purified by chromatography Bovine pancreatic dexoy ribonuclease I (DNase I) is an endonuclease which splits phosphodiester linkages, preferentially adjacent to a pyrimidine nucleotide yielding polynucleotides with a free hydroxyl group at the 3’ position and phosphate group at the 5’ position.
The optimum pH is 7.8. DNase I is activated by bivalent metals, and inhibited by chelating agents such as EDTA and SDS. DNase I can be stabilized against proteolytic digestion by 5mM CA²⁺.