QIAGEN Protease and QIAGEN Proteinase K

For protease digestion during DNA and RNA preparation

  QIAGEN Protease QIAGEN Proteinase K

Format: Lyophilized powder Ready-to-use solution
Amount: 7.5 AU or 4 x 7.5 AU 2 ml or 10 ml (20 mg/ml)
Activity: 45 mAU/mg protein >600 mAU/ml
Unit definition: One mAU is the activity that releases folin-positive amino acids and peptides corresponding to 1 µmol tyrosine per minute

Features and benefits

Both QIAGEN Protease and QIAGEN Proteinase K offer broad substrate specificity with high activity for a wide range of salt, denaturant and detergent (see table "Protease activity in commonly used buffers"), pH, and temperature conditions. Both proteases offer high activity in buffers commonly used in most DNA and RNA isolation procedures and are quality-guaranteed by QIAGEN. Subtle differences between the two enzymes as described below should be considered when planning protease digestions.

Protease activity in commonly used buffers*

Activity (%)
Proteinase K
Activity (%)

30 mM Tris,Cl 100 100
30 mM Tris,Cl; 30 mM EDTA; 5% Tween 20; 0.5% Triton X-100; 800 mM GuHCl 210 313
36 mM Tris,Cl; 36 mM EDTA; 5% Tween 20; 0.36% Triton X-100; 735 mM GuHCl 205 301
10 mM Tris,Cl; 25 mM EDTA; 100 mM NaCl; 0.5% SDS 78 128
10 mM Tris,Cl; 100 mM EDTA; 20 mM NaCl; 1% Sarkosyl 101 74
10 mM Tris,Cl; 50 mM KCl; 1.5 mM MgCl2; 0.45% Tween 20; 0.5% Triton X-100 159 106
10 mM Tris,Cl; 100 mM EDTA; 0.5% SDS 98 120
30 mM Tris,Cl; 10 mM EDTA; 1% SDS 38 203

* pH 8.0, 50<C, 1.25 µg/ml protease, 15 min incubation
† Buffer G2 used in QIAGEN Genomic-tip procedures for DNA isolation from blood, cell cultures, and tissue
‡ Recommended buffer conditions for protease digestion (Buffers B1+ B2) in the QIAGEN Genomic-tip protocol for bacterial DNA isolation

QIAGEN Proteinase K 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 which remains stable over a wide range of temperatures and pH values with substantially increased activity at 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:

QIAGEN Protease is a serine protease isolated from a recombinant Bacillus strain and 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:

Note: QIAGEN Protease is not compatible with Buffer ATL in DNeasy Tissue, DNeasy 96 Tissue, and the 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.

* 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.
† Users of the QIAamp 96 DNA Blood BioRobot Kit should resuspend each bottle of QIAGEN Protease with 10 ml distilled water.


Ordering Information
Product Contents Cat. No.
QIAGEN Protease (7.5 AU) 7.5 Anson units per vial (lyophilized) 19155
QIAGEN Protease (30 AU) 4 x 7.5 Anson units per vial (lyophilized) 19157
QIAGEN Proteinase K (2 ml) 2 ml (>600 mAU/ml, solution) 19131
QIAGEN Proteinase K (10 ml) 10 ml (>600 mAU/ml, solution) 19133