The Proteinase K enzyme is a member of the Peptidase family S8. Proteinase K is a broad-spectrum serine protease. Proteinase K is capable of digesting hair (keratin), henceforth, the name "Proteinase K". Proteinase K is activated by calcium, the enzyme digests proteins especially after hydrophobic amino acids (aliphatic, aromatic and other hydrophobic amino acids). Proteinase K is frequently utilized in molecular biology to digest protein and remove contamination from preparations of nucleic acid. Addition of Proteinase K to nucleic acid preparations rapidly inactivates nucleases which may otherwise degrade the DNA or RNA during purification. Proteinase K is greatly fitting to this application as the enzyme is active in the presence of chemicals which denature proteins, such as SDS and urea, chelating agents such as EDTA, sulfhydryl reagents, as well as trypsin or chymotrypsin inhibitors. Proteinase K is utilized for the destruction of proteins in cell lysates (tissue, cell culture cells) and for the release of nucleic acids, given that it quite effectively inactivates DNases and RNases.