Proteinase K from Tritirachium album

Unit definition.
The amount of protease K that can hydrolyze casein and produce 1umol tyrosine per minute is defined as one Unit at pH 7.5.

Application.
Proteolysis inactivation of nuclease used in the separation of DNA and RNA. Remove endotoxins that bind to cationic proteins such as lysozyme and ribonuclease A. It is reported that it can be used to separate liver, yeast and mung bean mitochondria. The localization of enzymes on the membrane was determined. Paraffin-embedded tissue sections were processed to expose the antigen binding sites used for antibody labeling. To digest prion proteins in brain tissue samples in the study of transmissible spongiform encephalopathy (TSE).

Biochemical / physiological behavior.
Protease K is a stable and highly reactive serine protease. Evidence from crystal and molecular structure studies showed that the enzyme belonged to the subtilisin family with active site catalytic triad (Asp39-His69-Ser224). It is stable in a wide range of environments: ph, buffer salts, detergents (SDS) and temperature. In 0.1-0.5% SDS, protease K can retain activity and digest various proteins and nucleases in the DNA preparation without compromising the integrity of the isolated DNA.