Highly characterized for more consistent performance, Proteinase K is a subtilisin-relatedserine protease that will hydrolyze a variety ofpeptide bonds. Proteinase K is active in a widerange of temperatures and buffers with optimalactivity between 20 and 60°C and a pH between 7.5and 12.0 (1, 2). Activity is stimulated when up to2% SDS or up to 4 M urea are included in the reaction(3). Calcium is important for thermostabilityof Proteinase K but it is not required for catalysis,therefore Proteinase K is also active in bufferscontaining chelating agents such as EDTA (4).
Lot-to-Lot Variability: Competitor ComparisonActivity measurements from three NEB lots of Proteinase K were compared to threelots from another vendor. Reported activity for all NEB lots is 800 Units/ml ± 10%(indicated as a black line with error bars). Direct measurement of the competitor’smaterial using an assay reported on the vendor’s literature, demonstrated a dramaticover-assessment of all three lots.
Activity Measurements: Competitor ComparisonActivity measurements from a single NEB lot were compared to a single lot from seven other vendors. Proteinase K from NEB is sold at 800 Units/ml ± 10% (indicatedas a black line with error bars), whereas most other vendors sell Proteinase Kas > 800 or > 600 Units/ml. While Proteinase K from some vendors was close tothe stated activity values, others varied significantly from the expected amount.Protein Concentration20 mg/ml, approximately, as determined by UV absorption at 280 nm.
Product Source
Engyodontium album (Tritirachium album)
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