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.

Proteinase K catalyzes the hydrolysis of keratin.

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.

Proteinase K catalyzes the hydrolysis of keratin.

General description

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 28,930Da. Active proteinase K is characterized with an unhydrolysed protein chain and autolysed polypeptide chains.

Unit Definition

One unit will hydrolyze urea-denatured hemoglobin to produce color equivalent to 1.0 µmole of tyrosine per min at pH 7.5 at 37 °C (color by Folin-Ciocalteu reagent).