Product Name

Proteinase K from Tritirachium album

Synonym

Endopeptidase K

Assay

≥800 units/mL

CAS Number

39450-01-6

Molecular Weight

mol wt 28.93 kDa

MDL number

MFCD00132129

Suitability

BioReagent, for molecular biology

l Physical and Chemical Information

Appearance

Colorless to Light Yellow to Light Brown buffered aqueous glycerol solution; Clear to Very Slightly Hazy

Physical form

Solution in 40% glycerol (v/v) containing 10 mM Tris-HCl, pH 7.5, with 1 mM calcium acetate.

l Biological Information

Biochem/Physiol Actions

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.

Proteinase K has a broad specificity and degrades many proteins even in the native state. It mainly cleaves the peptide bond adjacent to the carboxyl group of aliphatic and aromatic amino acids with blocked α-amino groups. The molecular weight of proteinase K from amino acid sequence is found to be 28,930 Da and from SDS-PAGE, it is found to be 28,500 Da. The optimum pH is between 7.5-9.0 and its isoelectric point is 8.9. Ca₂₊ (1-5 mM) is required for its activation. Proteinase K is inhibited by DIFP (diisopropylfluorophosphate) or PMSF (phenylmethylsulfonyl fluoride).

Application

The product has been used to study its pre-treatment effects on the silk fibroin. The aspects analysed in this study included the crystallographic properties of hydroxyapatite (HAp), and the microstructure and microhardness of the composites. The enzyme has also been used to facilitate the access of probes to rRNA using FISH techniques to detect pathogenic Staphylococcus aureus.

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.

Preparation Note

Solution in 40% glycerol (v/v) containing 10 mM Tris-HCl, pH 7.5, with 1 mM calcium acetate.

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).

l Storage

Storage temp.

2-8°C

l Precautions and Disclaimer

This product is for R&D use only, not for drug, household, or other uses.

l References

1. http://www.drugbank.ca

2. https://ncit.nci.nih.gov

3. https://www.ncbi.nlm.nih.gov