Proteinase K Ultrapure (1 g)

A recombinant subtilisin-related serine protease from QIAGEN, expressed in Komagataella phaffii (Pichia pastoris) and derived from Parengyodontium album (Tritirachium album). The 28.9 kDa enzyme is supplied as a lyophilized powder of the highest purity, with very low residual DNA (≤0.1 pg/mg) and enhanced 2.5-fold solubility. It delivers broad substrate specificity and strong activity across wide ranges of temperature and pH, efficiently digesting proteins — including DNases and RNases — during nucleic acid preparations without compromising DNA or RNA integrity. The enzyme cleaves peptide bonds adjacent to the carboxyl group of aliphatic, aromatic and other hydrophobic amino acids, and is routinely used for the isolation of genomic, plasmid and high-molecular-weight DNA and RNA.

The enzyme is typically applied at 50–200 µg/mL in nucleic acid preparations at pH 7.5–8.5 and 37–55°C, with incubation times ranging from 30 minutes to 18 hours. The working pH range spans 4.0–12.0 (optimum 7.5–8.5) with full activity maintained over several hours across pH 6.5–10.0. The working temperature range is 20–65°C, with optimum activity at 50–56°C. Activity is stimulated by 0.2–1% SDS or 1–4 M urea, and Ca²⁺ at 1–6 mM protects the enzyme from autolysis and increases its thermal stability. Proteinase K is not inactivated by chelating agents, chaotropic salts, detergents, metal ions, thiol reagents or trypsin-specific inhibitors.

Activity is declared at ≥35 U/mg lyophilizate and specific activity ≥45 U/mg protein, and the enzyme maintains these activity levels for at least 24 months at –20°C. It is highly soluble in water (≥50 mg/ml). One unit hydrolyzes urea-denatured hemoglobin producing color equivalent to 1 µmol tyrosine per minute at 37°C and pH 7.5.