Proteinase K

The Unsung Hero of COVID-19 Nucleic Acid Test.

Proteinase K is a powerful proteolytic enzyme isolated from Candida albicans that can digest natural Keratin, hence the name Proteinase K. It belongs to the S8 family of Serine Protease SB Superfamily. The main cleavage site of Proteinase K is the carboxy-terminal peptide bond of aliphatic and aromatic amino acids, which has high specific activity and is a key reagent for DNA extraction. The enzyme is active in a wide pH range (4-12.5) and at high temperature (50-70°C), and is widely used for the isolation and extraction of plasmid or genomic DNA and RNA.

Technical Features

Molecular Formula C29H27N2O12P

Molecular weight 626.504641

Storage conditions 2-8℃

Solubility H2O: 10mg/mL, easily soluble in water

Morphology 28.9 kilodaltons

Protein molecular weight >30U/mg, optimum pH range is 7.5-8.0

Enzyme activity >30U/mg, optimum pH range is 7.5-8.0, active within 0-70℃, optimum reaction temperature is 65℃

Proteinase K has super protein hydrolase activity, and the activity is not inhibited by SDS (sodium dodecyl sulfate), urea, EDTA (ethylenediaminetetraacetic acid), guanidine hydrochloride, guanidine isothiocyanate, etc. Moreover, the activity of Proteinase K can be enhanced by a certain level of detergent. These properties make the application of proteinase K involved in various fields of human life. For example, in the biology and medical industries, proteinase K is used in DNA and RNA extraction, processing of pre-hybridization specimens in in situ hybridization technology, and currently the most widely used in nucleic acid tests of infectious diseases such as COVID-19. The application of Proteinase K is not only limited to medical diagnosis and biology, but also can be alternative to other proteases with a narrower range of action under the premise of industrial production on a large scale, which can be used in leather industry, food handling (meat tenderization), water disinfection, feed production, paper making, brewing (wine clarification), amino acid preparation (degradation of feathers) etc.

Proteinase K is taking an important place in in COVID-19 Nucleic Acid Test that are now extensively penetrating into our daily lives.

Proteinase K is a primary component of the virus sampling solution that cleaves the virus to release nucleic acids and eliminate RNase (nucleolytic enzyme) to prevent RNA degradation of the virus. Proteinase K can also inactivate the virus, so that the virus protein is denatured and even inactivated, no longer infectious, to improve the safety of the transport and detection period. In the process of nucleic acid extraction, Proteinase K can degrade the protein bound to nucleic acid and promote the separation of nucleic acid, which plays a key role in the success of nucleic acid

With the outbreak of COVID-19 epidemic, the demand for nucleic acid testing has surged. Until late June 2020, nearly 90 million COVID-19 tests have been completed in China. Globally, the number is even more impressive. The working concentration of proteinase K in nucleic acid extraction experiments is about 50-200 μg/mL. Generally, about 100 μg of proteinase K is required to extract nucleic acid from one sample, while in practice, proteinase K is often used in higher amounts to increase the efficiency of nucleic acid extraction. The COVID-19 nucleic acid testing brings about a large demand for Proteinase K. The original balance of supply and demand for Proteinase K was rapidly broken, and Proteinase K became an important epidemic prevention material overnight. In the past, Proteinase K was far less well known than the role it played, and this ongoing epidemic has made people realize that Proteinase K is so important that it is the unsung hero in this battle between humans and viruses!