DNase I (not RNase FREE): Description: Bio Basic Inc’s DNase I (catalogue DD0099) is an endonuclease derived from bovine pancreas that will degrade double-stranded DNA in the presence of divalent cations, producing 3”-OH oligonucleotides. Mg2+ I in the reaction solution causes the enzyme to produce nicks in doublestranded DNA, while in the presence of Mn2+, DNase I cleaves both strands of the DNA. DNase I is useful in nick translation for introducing single-stranded nicks that serve as primer sites for initiation of DNA synthesis and for cloning random DNA fragments by cleaving double-stranded DNA. Bio Basic Inc.’s DNase I is a chromatographically pure preparation. It is offered as lyophilized powder with an approximately activity of 500 Kunitz U/mg. For greatest stability, it is important that DNAse be dissolved at a concentration of at least 1mg/ml in 50% Glycerol with 20mM Tris-Cl, pH 7.5, and 1mM MgCl2. This solution can be stored at -20ºC for at least a year.
Recommended 1X Reaction Buffer: 40mM Tris-HCl (pH 8.0), 2.5mM (up to 10mM) MgSO4, 1mM (up to 10mM) CaCl2 Note: If starting material contains EGTA, EDTA, other chelating reagents, and/or high concentration of salts, higher concentration of Mg and Ca are recommended.
Heat Inactivation: 10 minutes at 65°C in the presence of Stop Solution.
Inhibitors: EGTA; EDTA (7); salt concentrations >100mM will reduce DNase activity.
Molecular Weight: 31,000 Daltons.
Requirement: Ca2+ and Mg2+ or Mn2+
Source: Bovine pancreas.
Storage Temperature: Store at –20°C. Avoid exposure to frequent temperature changes. See the expiration date on the Product Information Label. Stop Solution: 20mM EGTA (pH 8.0).
Unit Definition: One unit of DNase is defined as the amount required to completely degrade 1µg of lambda DNA in 10 minutes at 37°C in 50µl of a buffer containing 40mM Tris-HCl (pH 8.0), 2.5mM (up to 10mM) MgSO4, 1mM (up to 10mM) CaCl2. Under these assay conditions one unit of DNase activity is approximately equal to one Kunitz unit. See the unit concentration on the Product Information Label.
