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.