Proteinase K is a highly active stable endopeptidase with a broad spectrum of action was isolated by E. Merk's Darmstadt Biochemical Research Department in 1970 from a culture filtrate of the fungus, Tritirachium album Limber. This fungus is able to grow on Keratin (e.g., wool, horn particles) as the sole source of carbon and nitrogen. The isolated protease was, therefore, given the K designation.
Proteinase K is useful for the proteolytic inactivation of nucleases during the isolation of DNA and RNA. It is also useful in removal of endotoxins bound to cationic proteins such as lysozyme and ribonuclease A. It is reported to be useful for the isolation of hepatic, yeast, and mung bean mitochondria. It is useful in determination of enzyme localization on membranes. It is also used in treatment of paraffin embedded tissue sections to expose antigen binding sites for antibody labeling. Proteinase K is used in digestion of proteins from brain tissue samples for prions in Transmissible Spongiform Encephalopathies (TSE) research.
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.
Grade: Molecular biology reagent
Specific Activity: >30 mAnson u/mg
Key Applications: Isolation of DNA and RNA
Application Areas: Molecular Biology
Product Type: Biochemicals
Biochemical Category: Amino Acids & Peptides
Chemical Class: Amino Acids & Peptides
Extinction Coefficient (E1%): E1%= 14.2 (280 nm,10 mM NaCl and 5 mM CaCl2, pH 8.0) (Lit.)
Presentation: White Powder
Format: Powder
Isoelectric point (pI): pI 8.9 (Lit.)
pH: 7.5 -12.00 (denatured hemoglobin as substrate) (Lit.)
Foreign activity: RNase <5x 10-4 u/mg DNase: <5x10-4 u/mg
NOTES:
Inhibition - Proteinase K belongs to the group of serine proteases with an easily esterifed serine fragment at the active center and, as with other proteases in this group, e.g. trypsin, chymotrypsin, is inactivated by diisopropylfluorophosphate or phenylmethane sulfonyl fluoride. Also inhibited by AEBSF and trypsin inhibitor. Metallic ion complexing agents, e.g., chelate formers such as EDTA and sulfhydryl reagents, have no effect on the activity of Proteinase K.
Specificity: Proteinase K cleaves peptide bonds mostly after the carboxyl group of N-substituted hydrophobic aliphatic and aromatic amino acids, as shown by specificity trials with amino acid-4-nitroacilides. Thus, it shows similarities with alkaline Asperigillus proteases. However, unlike the latter, Protease K also cleaves peptide amides, comparable to the alkaline serine-proteases from Bacillus species. The specificity of ester cleavage is also high.
Solubility: Soluble in water.
Storage & Handling: +4°C, dessicate
Certifications: DNase, RNase free