Proteinase K CAS 39450-01-6

Proteinase K is named proteinase K because of its ability to digest keratin (kratin). The proteinase K family contains a variety of intracellular peptidases secreted by fungi, yeast and Gram-negative bacteria, among which the enzymes secreted by bacteria have a high degree of sequence similarity (>55%). Candida albicans (Tritirachium albumLimber) secreted to produce proteinase K is the model protein of this family. Proteinase K has cleavage activity on most substrates, but prefers peptide chains with aliphatic and aromatic hydrocarbons. It is a serine protease with a typical serine active site: Asp39–His69–Ser224. It contains a single peptide chain with 277 amino acids, 2 disulfide bonds, a vacant cysteine ​​site and two calcium ion binding sites.

The application of proteinase K is mainly to remove DNase and RNase during nucleic acid extraction, to remove histone bound to the genome, and to inactivate alkaline phosphatase. At present, molecular biology technology has been applied to many detection standards, such as genetically modified detection, animal attribute detection, pathogenic microorganism detection, etc. In molecular biology detection, the extraction quality of nucleic acid directly affects the amplification efficiency of subsequent PCR reactions. Many standards include the addition of proteinase K digestion to the nucleic acid extraction step in order to extract purer nucleic acids. In order to protect nucleic acids, molecular biology nucleic acid extraction experiments usually contain reagents such as EDTA. Since EDTA can complex with metal ions, the enzymatic activity may be affected; and digestion is usually carried out at pH 8.0 and 55 °C. Enzyme activity is affected by different pH and temperature conditions.