QIAGEN Protease and Proteinase K

QIAGEN Protease and QIAGEN Proteinase K offer broad substrate specificity with high activity for a wide range of reaction conditions. QIAGEN Proteinase K in 2 mL and 10 mL pack sizes is dedicated for use in various QIAGEN kits (please see list in the Principle section below). As a sample prep expert, QIAGEN also offers Proteinase K as lyophilized powder (Proteinase K Powder). Both proteases offer high activity in buffers commonly used in most DNA and RNA isolation procedures and are quality-guaranteed by QIAGEN.

QIAGEN Protease and QIAGEN Proteinase K 

QIAGEN Protease and QIAGEN Proteinase K offer broad substrate specificity with high activity in buffers commonly used in most DNA and RNA isolation procedures. Both enzymes are quality-guaranteed by QIAGEN. 

QIAGEN Protease is particularly stable and active at high pH. In Tris-containing buffers of alkaline pH (7.5–10.5) QIAGEN Protease displays 30 to 40% higher specific activity than Proteinase K. 
In the presence of strong denaturants, such as urea (0.75–3 M urea) or guanidine HCl (0.5–3.0 GuHCl), the specific activity is comparable to that of Proteinase K, provided the EDTA concentration is less than 8 mM. 
QIAGEN Protease shows increased activity in the presence of urea and guanidine HCl. Similar stimulation is obtained upon the addition of up to 1% SDS. Enzymatic activity also increases as a function of 
temperature (30–55°C). For more detailed information, refer to the QIAGEN Protease Product Sheet in the Resources section.

The enzyme can be easily inactivated by incubation at 70°C for 15 minutes.
QIAGEN Protease is not inhibited by up to 100 mM EDTA in Tris·Cl buffers. However, in the presence of greater than 1% SDS or other strong denaturants, the EDTA concentration must be less than 8 mM.

Proteinase K powder

Proteinase K powder is a lyophilized, white powder, highly active with exceptional lot-to-lot consistency (see figure “High lot-to-lot consistency Proteinase K powder”), ensuring reproducibility for stable working conditions, repeatable and reliable experiment results. Proteinase K powder is highly stable when stored at -20°C (see figure “Proteinase K powder stability”).

Proteinase K powder specifications:

• No detected exonuclease, endonuclease or RNase activity
• Solubility in water ≥20 mg/mL; activity ≥30 U/mg lyophilizate; specific activity ≥40 U/mg protein; protein content ≥70%; DNA content ≤10 pg/mg
• Shipping conditions: Ambient temperature

Technical specifications

QIAGEN Proteinase K (in 2 mL and 10 mL pack sizes) is a subtilisin-type protease isolated from the saprophytic fungus Tritirachium album and is particularly suitable for short digestion times. It possesses a high specific activity that remains stable over a wide range of temperatures and pH values with substantially increased activity at a higher temperature. Soluble calcium is not essential for enzymatic activity. This means that EDTA, which is used to inhibit Mg²⁺-dependent enzymes, such as nucleases, will not inhibit Proteinase K activity. Proteinase K is supplied in the following QIAGEN kits:

• QIAamp DNA Mini Kit
• QIAamp Fast DNA Stool Mini Kit
• DNeasy Blood & Tissue Kit
• DNeasy 96 Blood & Tissue Kit
• QIAamp DNA Micro Kit
• QIAamp MinElute Media Kit
• QIAamp Media MDx Kit

QIAGEN Protease is a serine protease isolated from a recombinant Bacillus strain. It is an economical alternative to Proteinase K for isolation of native DNA and RNA from a variety of sources. QIAGEN Protease is completely free of DNase and RNase activities. QIAGEN Protease is supplied in the following QIAGEN kits:

• QIAamp DNA Blood Mini, Midi and Maxi Kits
• QIAamp 96 DNA Blood Kit
• Blood & Cell Culture DNA Kits
• QIAamp Virus BioRobot 9604 Kit
• QIAamp DNA Blood BioRobot MDx Kit
• QIAamp DSP Virus Kit
• QIAamp DSP DNA Blood Mini Kit

Note: Users of manual QIAamp DNA Blood Kits and QIAGEN Blood & Cell Culture DNA Kits should resuspend each bottle of QIAGEN Protease with 7 mL distilled water.

Note: Users of the QIAamp DNA Blood BioRobot 9604 Kit should resuspend each bottle of QIAGEN Protease with 10 mL distilled water.

Note: QIAGEN Protease is not compatible with Buffer ATL in the DNeasy Tissue, DNeasy 96 Tissue and QIAamp DNA Mini Kit. In the presence of >0.5% SDS, >1% sarkosyl or high concentrations of other detergents, the EDTA concentration must be <8 mM for full activity over extended incubation times.

Instructions for using QIAGEN Protease, QIAGEN Proteinase K and Proteinase K Powder are provided in the corresponding kit handbook.

QIAGEN Protease, QIAGEN Proteinase K and Proteinase K Powder provide protease digestion during DNA and RNA preparation. Subtle differences between the enzymes should be considered when planning protease digestions.