Proteinase K is a serine protease that is used in cell
culture to digest proteins in cell lysates and release
nucleic acids. It degrades proteins even in the presence
of detergents. Proteinase K cleaves peptide bonds at
the carboxylic sides of aliphatic, aromatic, or
hydrophobic amino acids. The smallest peptide to be
hydrolyzed by this enzyme is a tetrapeptide.