Proteinase K

Ready- to-use enzyme for DNA and RNA isolation.

Description

Proteinase K is a non-specific serine protease having a very high specific activity. It is used to purify target material from contaminating proteins, for the isolation of mRNA or high molecular weight DNA and to inactivate other enzymatic activities. Proteinase K is active with or without the presence of SDS, EDTA and urea. Finnzymes´ proteinase K is isolated from Tritirachium album and it is very stable in the storage buffer at +4°C and at –20°C.

Applications

• Isolation of high molecular weight DNA
• Isolation of plasmid and genomic DNA
• Isolation of RNA
• Inactivation of RNase and DNase activities

Advantages

• Ready to use, provided in liquid form containing 50 % glycerol
• Smaller contamination risk with liquid form
• Can be stored at –20°C still having the enzyme in liquid form
• Excellent stability

Concentration and activity

The concentration of Proteinase K is 20 mg/ml and the specific activity is >30 units/mg. Proteinase K is supplied in liquid form diluted in storage buffer.

Proteinase K activity in commonly used buffers
Stability of Proteinase K in 50 % glycerol buffer at different temperatures

Storage buffer

20 mM Tris-HCl (pH 7.4), 1 mM CaCl₂, 50 % Glycerol.

Quality control

Unit definition
One unit is defined as the amount of enzyme that liberates folin-positive amino acids and peptides corresponding to 1 µmol tyrosine under the assay conditions in 1 minute using hemoglobin as substrate.

16-hour incubation
A 50 µl reaction containing 1 µg of λ DNA and 1.8 U of enzyme incubated for 16 hours at 37°C resulted in the same DNA band as that produced without the enzyme.

Exonuclease activity
Incubation of 6 U for 4 hours at 37°C in 50 µl assay buffer with 1 µg sonicated [³H]-DNA (2 x 10⁵ cpm/µg) released <0.2 % of radioactivity.

Endonuclease activity
Incubation of 1.8 U with 1 µg φX174 RFI DNA (4 hours, 37°C, 50 µl) gave <5 % conversion to RFII.

RNase activity
Incubation of 6.0 U with 1 µg MS2 RNA (4 hours, 37°C, 50 µl) resulted in the same RNA band as that produced without the enzyme.

Common features
Proteinase K has two binding sites for Ca²⁺. Calcium acts as a stabilizing factor of the enzyme. When calcium is removed from the solution, the activity of proteinase K decreases slowly.

Storage and stability

Stable for one year from the assay date. Recommended storage temperature -20°C.

Ordering information

Bulk quantities also available in lyophilized form.

Proteinase K	Concentration	Size
F-202S	20 mg/ml	1 ml
F-202L	20 mg/ml	5 x 1 ml