Proteinase K is an extracellular endopeptidase. It is synthesized by the mold Tritirachium album Limber. Proteinase K belongs to a new subfamily of the subtilisins. It is a 277 amino acid protein with a molecular weight of 28,930 Da. Active proteinase K is characterized with an unhydrolysed protein chain and autolysed polypeptide chains.
Synonyms: Endopeptidase K
MDL Number: MFCD00132129
Storage: -20C
Application: Useful for the proteolytic inactivation of nucleases during the isolation of DNA and RNA.Removes endotoxins that bind to cationic proteins such as lysozyme and ribonuclease A.Reported useful for the isolation of hepatic, yeast, and mung bean mitochondriaDetermination of enzyme localization on membranesTreatment of paraffin embedded tissue sections to expose antigen binding sites for antibody labeling.Digestion of proteins from brain tissue samples for prions in Transmissible Spongiform Encephalopathies (TSE) research.
Biochem Physiol Actions: Proteinase K is a stable and highly reactive serine protease. Evidence from crystal and molecular structure studies indicates the enzyme belongs to the subtilisin family with an active-site catalytic triad (Asp39-His69-Ser224). It is stable in a broad range of environments: pH, buffer salts, detergents (SDS), and temperature. In the presence of 0.1-0.5% SDS, proteinase K retains activity and will digest a variety of proteins and nucleases in DNA preparations without compromising the integrity of the isolated DNA.