dsDNase HL (2500 U)

A 43.3 kDa heat-labile recombinant endonuclease from QIAGEN, derived from a cold-water eukaryotic organism and recombinantly expressed in Pichia pastoris, this enzyme displays high specific activity towards double-stranded DNA while leaving single-stranded DNA or RNA undamaged. It hydrolyzes phosphodiester linkages, yielding oligonucleotides with a 5′-phosphate and 3′-hydroxyl groups, and is intended for the rapid and safe purification of RNA or protein samples from contaminating DNA.

The enzyme is supplied in a buffer containing 20 mM Tris-HCl pH 8.0, 20 mM NaCl, 2 mM MgCl₂, 1 mM CaCl₂, and 50% (v/v) glycerol. One unit is defined as the amount of enzyme that causes an increase in absorbance at 260 nm of 1.0 in 30 minutes at 37°C in 50 mM Tris-HCl buffer, pH 8.0 (25°C) supplemented with 5 mM MgCl₂, 0.1 mg/mL BSA, and 0.5 mg/mL herring sperm DNA. The enzyme concentration is ≥2 U/µL, with optimum activity at pH 7.0–8.0 and temperatures of 10–47°C, requiring Mg²⁺ ions (2–4 mM optimum), with Ca²⁺ ions (1–5 mM optimum) further enhancing activity. Quality control testing confirms protein purity >90%, with no RNase activity and no proteolytic activity detected.

Typical uses include digestion of dsDNA (such as plasmid or genomic DNA), rapid purification of RNA and protein samples, and decontamination of PCR, qPCR master mixes, or other diagnostic kits. The enzyme can be quickly and irreversibly inactivated by heat treatment, with complete inactivation achieved by incubation at 52°C for 15 minutes in the presence of 1–10 mM DTT or TCEP. It must be shipped on dry ice and stored at −20°C in a freezer without a defrost cycle, or at −80°C for long-term storage, with a stated shelf life of 36 months.