Proteinase K (recombinant), PCR grade

Recombinant enzyme

Proteinase K (recombinant),  PCR grade
Proteinase K is a broad-range endolytic protease widely used for digestion of proteins in nucleic acid preparations. It degrades proteins even in the presence of detergents.

Thermo Scientific Proteinase K is an endolytic protease that cleaves peptide bonds at the carboxylic sides of aliphatic, aromatic, or hydrophobic amino acids. The Proteinase K is classified as a serine protease (see Reference 1). The smallest peptide to be hydrolyzed by this enzyme is a tetrapeptide.


  • Ready-to-use solution
  • Active in a wide range of reaction conditions


  • Isolation of genomic DNA from mouse tail
  • Isolation of genomic DNA from cultured cells
  • Removal of DNases and RNases when isolating DNA and RNA from tissues or cell lines (see References 2, 3)
  • Determination of enzyme localization (see​ Reference 4)
  • Improving cloning efficiency of PCR products (see​ Reference 5)


  • The recommended working concentration of Proteinase K is 0.05 to 1 mg/mL. The activity of the enzyme is stimulated by 0.2 to 1% SDS or by 1 to 4 M urea (see​ Reference 3)
  • Ca2+ protects Proteinase K against autolysis, increases the thermal stability, and has a regulatory function for the substrate binding site of Proteinase K (see​ Reference 7)
  • Stable over a wide pH range: 4.0 to 12.5, optimum pH 7.5 to 8.0 (see​ Reference 8)
  • Optimum activity at 50 to55°C
  • Rapid denaturation of enzyme occurs at temperatures above 65°C
Definition of Activity Unit
  • One unit of the enzyme liberates Folin-positive amino acids and peptides corresponding to 1 µmol tyrosine in 1 min at 37°C using denatured hemoglobin as substrate.
  • Enzyme activity is assayed in the following mixture: 0.08 M potassium phosphate (pH 7.5), 5 M urea, 4 mM NaCl, 3 mM CaCl2 and 16.7 mg/mL hemoglobin.
  • Inhibitors: Proteinase K is not inactivated by metal chelators, by thiol-reactive reagents, or by specific trypsin and chymotrypsin inhibitors.
  • Phenylmethylsulfonyl fluoride and diisopropyl phosphorofluoridate completely inhibit the enzyme (see Reference 1).
Molecular Weight28.9 kDa monomer (see Reference 6)
Quality ControlThe absence of endo-, exodeoxyribonucleases, and ribonucleases confirmed by appropriate quality tests.
SourcePichia pastoris cells with a cloned gene encoding Tritirachium album endolytic protease (Proteinase K).
Storage BufferThe enzyme is supplied in: 10 mM Tris-HCl (pH 7.5), containing calcium acetate and 50% (v/v) glycerol.
Storage Condition-20 C


  1. W. Ebeling et al., Proteinase K from Tritirachium album Limber. Eur. J. Biochem. 47, 91-97 (1974).

  2. U. Wiegers, H. Hilz, A new method using ‘proteinase K’ to prevent mRNA degradation during isolation from HeLa cells. Biochem. and Biophys. Res. Commun. 44(2), 513-519 (16 July 1971).

  3. H. Hilz et al., Stimulation of proteinase K action by denaturing agents: application to the isolation of nucleic acids and the degradation of “masked” proteins. Eur. J. Biochem. 56(1), 103-108 (1 August 1975).

  4. D. Brdiczka, W. Krebs, Localization of enzymes by means of proteases. Biochim. Biophys. Acta. 297(2), 203-212 (1973).

  5. J. S. Crowe et al., Improved cloning efficiency of polymerase chain reaction (PCR) products after proteinase K digestion. Nucleic Acids Res. 19, 184 (1991).

  6. K. D. Jany et al., Amino acid sequence of Proteinase K from mold Tritirachtum album Limber Proteinase K – a subtilisn related enzyme with disulfide bonds. FEBS Lett. 199, 139-144 (1986).

  7. J. Bajorath et al., The enzymatic activity of proteinase K is controled by calcium. Eur. J. Biochem. 176, 441-447 (1988).

  8. W. Ardelt, M. Laskowski Jr., Turkey ovomucoid third domain inhibits eight different serine proteinases of varied specificity on the same ...Leu18-Glu19... reactive site. Biochemistry. 24(20), 5313-5320 (24 September 1985).