PROTEINASE K Molecular Biology Grade

Proteinase K MB Grade - lyophilized or liquid version tailored to your application.

Boost the efficiency of protein digestion with custom-made enzymes. BLIRT - expert in Proteinase K production for over 15 years. Certified manufacturing process ISO 13485 resulting in the highest quality product with a very high batch-to-batch consistency.
  • Short lead time for bulk quantities.
  • Portioning service with the possibility of white labeling.
  • High throughput for aliquoting of the liquid form (up to several million samples monthly).
RP100, RP100B, RP101B, RP102B, RP103B-5, RP103B-10, RP103B-50, RP103B, RP103B-C, RP107B, RP107B-1, RP107B-5
Available Options:
SKU Form
Proteinase K MB grade bulk RP103B Lyophilized powder Ask for an offer
Proteinase K Solution bulk RP107B Solution Ask for an offer

PROTEINASE K Molecular Biology Grade

Proteinase K  Molecular Biology Grade (PCR Grade ) from Parengyodontium album (Tritirachium album) is a subtilisin-related serine protease. It is a broad-spectrum endopeptidase with an extraordinary specificity allowing highly effective digestion of proteins in many laboratory applications. The enzyme is expressed in Pichia pastoris, and undergoes extensive purification to yield the highest quality product.

Proteinase K MBG is active under a wide range of reaction conditions, including elevated temperatures and the presence of SDS. As a result, this enzyme is widely used for the digestion of proteins, including DNases and RNases, during nucleic acid preparations without compromising the integrity of isolated DNA or RNA.

Proteinase K MBG is free of exonucleases, endonucleases, and ribonucleases. Also, check our Proteinase K NGS Grade



  • Recombinant broad-spectrum non-specific protease derived from Tritirachium album and over-expressed in Pichia pastoris.
  • High activity and exceptional purity.
  • Active at high temperatures (up to 56 °C) and under denaturing conditions (e.g. in the presence of urea and/or SDS), which makes it ideal for digesting proteins in a variety of applications.
  • Stable over a wide pH range: 4.0–12.5 (optimum pH 7.5–8.0).
  • Decreased amount of host DNA (≤ 10 pg/mg / MBG or ≤ 0.1 pg/mg NGS).
  • Available as powder, lyophilized “cake” or liquid.


  • Extraction of DNA and RNA from different starting materials.
  • Removal of DNases and RNases during nucleic acid isolation.
  • Purification of samples contaminated with different protein
  • Automated isolation stations


One unit of Proteinase K hydrolyzes urea-denaturated hemoglobin producing color equivalent of 1 μmol tyrosine per 1 min at 37°C and pH 7.5 (Folin & Ciocalteu’s method), 1 U = 1 mAnsonU.


Check our Client’s success stories: Case Study

Proteinase K purity

The high purity of Proteinase K increases the sensitivity and specificity of molecular biology applications, especially with low input and variable quality of tested DNA. The  NGS– and MB-grade versions in powder form are characterized by the low content of host cell DNA: ≤0.1 and ≤10 pg/mg, respectively. Below, you can see the comparison of Proteinase K MBG and NGS Grade (Table 1 ).

Proteinase K comparison


Lyophilized Proteinase K activity

BLIRT’s protease activity is measured with its equivalent products from four various competitors. The same experimental conditions, with the unchanged concentration of Proteinase K, are used. The enzyme activity test, using hemoglobin as a substrate, shows ≥30 U/mg declared activity for all tested suppliers (Figure 1).

Proteinase K Activity


Lyophilized Proteinase K  Stability

Lyophilized protease MBG activity ≥30 U/mg is guaranteed by Certificate of Analysis for up to two years when stored at -20°C. Additional experiments reveal only <14% activity loss after almost three-year storage at -20°C, which is still above-declared ≥30U/mg (Figure 2). Such a highly stable activity is a significant feature in molecular biology kit development.

Proteinase K Stability


 Liquid Proteinase K  Stability

Proteinase K MBG solution is recommended to be stored at -20°C, +4°C, or room temperature to guarantee activity over 800U/ml during at least 24 months. There is no detectable difference in the stated enzyme activity stored at +4°C and +37°C for up to 18 months (data not shown). Stability examinations at all tested temperatures are in progress. Liquid Proteinase K remains in its activity when stored at RT for at least 24 months (Figure 3). Importantly, liquid protease remains in its declared activity despite possible exposures to temperature oscillations, e.g. during transportation or experiments.


Batch-to-batch consistency

BLIRT’s Proteinase K MBG activity measurements demonstrate very low batch-to-batch variability, both in a powder and liquid form of protease  (Figure 4). Such a high reproducibility enables stable working conditions, and therefore repeatable and reliable experiments’ results.

activity liquid Proteinase K



Lyophilized Proteinase K MB Grade

  • Solubility in water:   

≥ 20 mg/ml


  • Activity

≥ 30 U/mg lyophilizate

≥ 40 U/mg protein


  • Protein content

≥ 70% Protein content is determined by measuring absorbance at 280 nm.


  • DNA content

≤ 10 pg/mg by qPCR


Proteinase K stock solution preparation

  • 20  mg/ml solutions: use purified water for immediate use.
  • 20 – 50 mg/ml solutions: use 50 mM Tris-HCl, pH = 7.5-8.0, 1-5 mM Ca2+ (calcium chloride, calcium acetate) for immediate use; or 10 mM Tris-HCl, pH = 7.5-8.0, 1-5 mM Ca2+ (calcium chloride, calcium acetate), 50% glycerol for long-term storage. 

Liquid Proteinase K MB Grade

  • Concentration

20 mg/ml


  • Activity

≥ 800 U/ml


  • DNA content

≤ 200 pg/ml by qPCR

PROTEINASE K Molecular Biology Grade - Product Specification (Powder)

PROTEINASE K Molecular Biology Grade - Product Specification (Solution)

PROTEINASE K Molecular Biology Grade - Flyer

  • Proteinase K MB and NGS grade is water soluble at the optimal concentration of 20 and 50 mg/ml, respectively. We also recommend to prepare solutions using 10-50 mM Tris-HCl, pH = 7.5-8.0, 1-5 mM Ca2+ (calcium chloride, calcium acetate) for immediate use or 10 mM Tris-HCl, pH = 7.5-8.0, 1-5 mM Ca2+ (calcium chloride, calcium acetate), 50% glycerol for long-term storage.

  • Proteinase K activity increases with temperature, which is up to 56 °C.

  • Heating proteinase K to 95°C for 10 minutes incompletely inactivates it. To our knowledge, Proteinase K cannot be completely heat-inactivated. Protease inhibitors such as PMSF and AEBSF can also be used to help inactivate Proteinase K.

  • Proteinase K can be used in a wide range of pH levels from 4.0 to 12.5, with its optimum at 7.5-8.0.


PROTEINASE K Molecular Biology Grade - Powder - CoA

PROTEINASE K Molecular Biology Grade - Solution -CoA

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