For protease digestion during DNA and RNA preparation
QIAGEN Protease and QIAGEN Proteinase K offer broad substrate specificity with high activity for a wide range of reaction conditions. 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 offer broad substrate specificity with high activity in buffers commonly used in most DNA and RNA isolation procedures as well as in a wide range of salt, denaturant, and detergent (see table "Protease activity in commonly used buffers"), pH, and temperature conditions. Both enzymes are quality-guaranteed by QIAGEN.
Protease activity in commonly used buffers*
QIAGEN Proteinase K
30 mM Tris·Cl
30 mM Tris·Cl; 30 mM EDTA; 5% Tween 20; 0.5% Triton X-100; 800 mM GuHCl†
36 mM Tris·Cl; 36 mM EDTA; 5% Tween 20; 0.36% Triton X-100; 735 mM GuHCl‡
10 mM Tris·Cl; 25 mM EDTA; 100 mM NaCl; 0.5% SDS
10 mM Tris·Cl; 100 mM EDTA; 20 mM NaCl; 1% Sarkosyl
10 mM Tris·Cl; 50 mM KCl; 1.5 mM MgCl2; 0.45% Tween 20; 0.5% Triton X-100
10 mM Tris·Cl; 100 mM EDTA; 0.5% SDS
30 mM Tris·Cl; 10 mM EDTA; 1% SDS
* 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
7.5 AU or 4 x 7.5 AU
2 ml or 10 ml (20 mg/ml)
45 mAU/mg protein
>318 mAU/ml (30°C)
One mAU is the activity that releases folin-positive amino acids and peptides corresponding to 1 µmol tyrosine per minute
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 the following QIAGEN kits:
QIAamp DNA Mini Kit
QIAamp DNA Stool Mini Kit
QIAamp 96 DNA Swab BioRobot Kit
DNeasy Tissue Kit
DNeasy 96 Tissue Kit
QIAamp DNA Micro Kit
QIAamp MinElute Media Kit
QIAamp UltraSens Virus Kit
QIAamp Media MDx Kit
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 the following QIAGEN kits:
QIAamp DNA Blood Mini, Midi, and Maxi Kits
QIAamp 96 DNA Blood Kit
Blood & Cell Culture DNA Kits
QIAamp DNA Blood BioRobot 9604 Kit
QIAamp Virus BioRobot 9604 Kit
QIAamp DNA Blood BioRobot MDx Kit
QIAamp DSP 96 Virus 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 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.
Instructions for using QIAGEN Protease or QIAGEN Proteinase K are provided in the corresponding kit handbook.
QIAGEN Protease and QIAGEN Proteinase K provide protease digestion during DNA and RNA preparation. Subtle differences between the enzymes should be considered when planning protease digestions.
2.5 ml (100 mg/ml; 7000 units/ml, solution)
Unit definition: That amount of enzyme causing the hydrolysis of RNA at a rate such that k (velocity constant) equals unity (Kunitz units) at 25°C and pH 5.0.