Vaccine Lab / Alfa Chemistry
Proteinase K
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Proteinase K

Proteinase K is a serine protease of eukaryotic origin, isolated from the fungus Tritirachium album Limber. This enzyme can digest keratin in hair, which leads to its name being proteinase K (K stands for keratin). Protease K belongs to the peptidase family S8 (subtilisin) with a molecular weight of 28,900 daltons (28.9 kDa). The enzyme has a fairly broad specificity, but with a preference for cleavage of peptide bonds C-terminal to aliphatic and aromatic amino acids, particularly alanine [1]. Due to its broad substrate specificity, high activity and ability to digest natural proteins, proteinase K has been widely used in molecular biology.

Proteinase K

Product Details

Product NameProteinase K
CAS Number39450-01-6
Molecular Weight28.9 kDa
AppearanceLyophilized powder
Specific Activity≥30 units/mg protein
Storage ConditionStore at -20 °C
NoteThis product is for research use only.

Product Features

  • Our Proteinase K remains stable over a wide pH range (optimum between 6.5-9.5) and relatively high temperatures (optimum between 50-65 °C).
  • Our Proteinase K is active in the presence of protein denaturing chemicals such as SDS and urea, chelating agents such as EDTA, hydrogen sulfide reagents and trypsin or chymotrypsin inhibitors.
  • Our Proteinase K is DNase free, RNase free and has no nucleic acid residues.

Product Activity

Proteinase K activity in commonly used buffers is shown in the following table [2].

Buffer (pH = 8.0, 50 °C, 1.25 µg/mL protease K, 15 min incubation)Proteinase K activity
30 mM Tris·Cl100%
30 mM Tris·Cl; 30 mM EDTA; 5% Tween 20; 0.5% Triton X-100; 800 mM GuHCl313%
36 mM Tris·Cl; 36 mM EDTA; 5% Tween 20; 0.36% Triton X-100; 735 mM GuHCl301%
10 mM Tris·Cl; 25 mM EDTA; 100 mM NaCl; 0.5% SDS128%
10 mM Tris·Cl; 100 mM EDTA; 20 mM NaCl; 1% Sarkosyl74%
10 mM Tris·Cl; 50 mM KCl; 1.5 mM MgCl2; 0.45% Tween 20; 0.5% Triton X-100106%
10 mM Tris·Cl; 100 mM EDTA; 0.5% SDS120%
30 mM Tris·Cl; 10 mM EDTA; 1% SDS203%

Product Applications

  • Our Proteinase K is commonly used in molecular biology to digest proteins and remove contaminants from nucleic acid preparations.
  • Our Protease K is used in the separation of plasmids, genomic DNA or RNA.
  • Our proteinase K can inactivate RNases, DNases and enzymes in reactions.
  • Our proteinase K is used for the destruction of proteins in cell lysates (tissues, cell culture cells) and for the release of nucleic acids.
  • Our Proteinase K can analyze membrane structures by modifying proteins and glycoproteins on the cell surface.
  • Our Proteinase K can treat tissue sections to ensure effective infiltration of the probe during in situ hydridization.

Since the SARS-CoV-2 pandemic, research into the detection and treatment of Coronavirus has never stopped. Alfa Chemistry is committed to providing customers with the proteinase K used in the nucleic acid detection process to meet their various needs. If the product you are looking for is not in our catalog, please contact us. We will be happy to provide you with customized synthesis services.


  1. Ebeling, W.; et al. Proteinase K from Tritirachium album Limber. Eur. J. Biochem. 1974, 47: 91-97.
  2. Ag-Scientific. "Frequently asked questions about Proteinase K".

Our products and services are for research use only and cannot be used for any clinical purposes.

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