Proteinase K

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Proteinase K is an extracellular serine endoproteinase produced by Tritirachium album Limber. Proteinase K belongs to the peptidase family S8. Its predominant cleavage site is the peptide bond adjacent to the carboxyl group of aliphatic and aromatic amino acids with blocked α-amino groups. Proteinase K is a broad-spectrum protease that functions at wide pH and temperature ranges. The optimum pH and temperature for the activity of this protease were approximately pH 7.5-8.0 and 55°C, respectively. In addition, 0.2-1% sodium dodecyl sulfate (SDS) and 10mM carbamide can activate its activity.


The combination of these unique features makes Proteinase K as an important tool in scientific research and molecular diagnosis. Proteinase K can be used in the preparation of biological macromolecules by degrading the constitutive proteins of cells and removing nucleases such as DNases and RNases for RT-PCR. In nucleic acid vaccine and molecular diagnosis, it is also widely used for degrading proteinaceous impurities during the isolation of nucleic acids from biological samples.


Proteinase K

CUSAg (WUHAN HUAMEI BIOTECH CO.,LTD) has recently launched a batch of high- quality proteinase K. Our company's biochemical detection platform was used to characterize  the self-produced proteinase K and showing its high purity and enzyme activity. It is applied in the COVID-19 nucleic acid extraction kit and  completely digest various nucleases and other proteins.It can prevent  viral nucleic acid degradation and optimize extraction efficiency. Both liquid/lyophilized powder can be provided to meet the detection requirments of COVID-19/HCV/HBV.


Brand: CUSAg 

Presentation: Liquid or Lyophilized powder

Catalog Number: CSB-DP437A/CSB-DP578A

Source: Recombination 

Valid Period: 2-8℃ for 12 months, -20 ℃ for 18 months 

Purity: 90%±5% by SDS-PAGE 

Application: Genomic DNA Purification Kit, RNA Purification Kit, Gene diagnostic kit,

IHC, ISH and other possible application. 

Capacity: 30kg/Month

Calibration Curve

According to the absorbance A275 for the vertical axis, the different concentrations of tyrosine as the horizontal axis, the standard curve was drawn. Then, the enzyme activity was 30U/mg by calculating (Fig.1).

Unit definition:One unit is defined as the amount of enzyme that catalyzes the formation of 1 umol of tyrosine per minute at pH 7.5 at 37°C.


Fig.1 Calibrationcurve of L-tyrosine at 275 nm


Protein Purity

The purity and the molecular weight of CUSAg proteinase K were over 95% and 28.9 kDa by SDS-PAGE, respectively (Fig.2).

Fig.2 SDS-PAGE analysis ofproteinase K


The proteinase K powder was stored at 4°C for one year. Enzymetic activities were asaayed every month during one year.As shown in Fig.3, it indicates that proteinase K is stable and enzyme activity is maintained more than 95%.

Fig.3 The stability of proteinase K at 4℃