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Proteinase K from Tritirachium album

Suitable for manufacturing of diagnostic kits and reagents, lyophilized powder, ≥30 units/mg protein, for molecular biology

Endopeptidase K
CAS Number:
Enzyme Commission number:
EC Number:
MDL number:

biological source

fungus (Tritirachium album)

Quality Level


for molecular biology


lyophilized powder

specific activity

≥30 units/mg protein

mol wt

28.93 kDa


≤1 ppm DNA


diagnostic assay manufacturing

foreign activity

DNAse, Nickase and RNAse, none detected

shipped in

wet ice

storage temp.


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General description

Proteinase K is an extracellular endopeptidase. It is synthesized by the mold Tritirachium album Limber. Proteinase K belongs to a new subfamily of the subtilisins. It is a 277 amino acid protein with a molecular weight of 28,930 Da. Active proteinase K is characterized with an unhydrolysed protein chain and autolysed polypeptide chains.


Proteinase K catalyzes the hydrolysis of keratin.
Useful for the proteolytic inactivation of nucleases during the isolation of DNA and RNA.
Removes endotoxins that bind to cationic proteins such as lysozyme and ribonuclease A.
Reported useful for the isolation of hepatic, yeast, and mung bean mitochondria
Determination of enzyme localization on membranes
Treatment of paraffin embedded tissue sections to expose antigen binding sites for antibody labeling.
Digestion of proteins from brain tissue samples for prions in Transmissible Spongiform Encephalopathies (TSE) research.

Biochem/physiol Actions

Proteinase K catalyzes the hydrolysis of keratin.
Proteinase K is a stable and highly reactive serine protease. Evidence from crystal and molecular structure studies indicates the enzyme belongs to the subtilisin family with an active-site catalytic triad (Asp39-His69-Ser224). It is stable in a broad range of environments: pH, buffer salts, detergents (SDS), and temperature. In the presence of 0.1-0.5% SDS, proteinase K retains activity and will digest a variety of proteins and nucleases in DNA preparations without compromising the integrity of the isolated DNA.

Unit Definition

One unit will hydrolyze urea-denatured hemoglobin to produce color equivalent to 1.0 μmole of tyrosine per min at pH 7.5 at 37 °C (color by Folin-Ciocalteu reagent).


Health hazard

Signal Word


Hazard Statements

Hazard Classifications

Eye Irrit. 2 - Resp. Sens. 1 - Skin Irrit. 2

Storage Class Code

11 - Combustible Solids



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Certificate of Origin

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