Proteinase K (100 mg)

A recombinant subtilisin-related serine protease from QIAGEN, Proteinase K is supplied as a lyophilized powder. The 28.9 kDa enzyme is expressed in Komagataella phaffii (Pichia pastoris) and derived from Parengyodontium album (Tritirachium album), delivering broad-spectrum endopeptidase activity for efficient protein digestion in nucleic acid preparation workflows.

The lyophilized powder delivers ≥30 U/mg activity and ≥40 U/mg specific activity, with DNA content ≤10 pg/mg and no detected exonuclease, endonuclease, or RNase activity. It functions across a working pH range of 4.0–12.0 (optimum at pH 7.5–8.5) and a working temperature range of 20–65°C (optimum at 50–56°C). The enzyme is stimulated by denaturing agents such as 0.2–1% SDS or 1–4 M urea, and remains stable in the presence of Ca²⁺ (1–6 mM), chelating agents, chaotropic salts, detergents, metal ions, thiol reagents, and trypsin-specific inhibitors. It cleaves proteins preferentially behind hydrophobic amino acids, with a tetrapeptide being the smallest substrate hydrolyzed.

Typical use is 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 enzyme cleaves peptide bonds adjacent to the carboxyl group of aliphatic, aromatic and other hydrophobic amino acids, making it suitable for isolating genomic, plasmid and high molecular weight DNA and RNA, as well as digesting structural proteins and chromatin. The lyophilized powder maintains activity for at least 24 months when stored at –20°C in its original, unopened container and is shipped at ambient temperature.