Proteinase K (from Tritirachium album), MP Biomedicals
Supplier: MP BIOMEDICALS (FKA ICN BIOMED
A highly active stable endopeptidase with a broad spectrum of action was isolated by E.
- Presentation: White to off white lyophilized powder
- Isoelectric point (pI): 8.9
- pH optimum (denatured hemoglobin as substrate): pH 7.5 to 12.00
- Soluble in water (1 mg/ml)
Proteinase K is suitable for both protein and nucleic acid isolation. Exhibits proteolytic activity on proteins, peptides, glycoproteins, amides and esters. Also active with nitroanilides of amino acids with protected amino groups, excluding arginine. Useful in the isolation of DNA and RNA, in the analysis of membrane structures and protein structure. Addition of either 0.5 to 1% of sodium dodecyl sulfate or 1-4 mmol/L of urea increases the activity, because the substrates are more easily attacked when denatured. In experiment to recover the undigested DNA, proteins were digested with 0.1 mg/ml of proteinase K.
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 to 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 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.
Merk's Darmstadt Biochemical Research Department in 1970 from a culture filtrate of the fungus, Tritirachium album Limber, suitable for both protein and nucleic acid isolation, it exhibits proteolytic activity on proteins, peptides, glycoproteins, amides and esters. Also active with nitroanilides of amino acids with protected amino groups, excluding arginine.
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