Proteinase K from the fungus Engyodontium album is a non-specific serine protease that

 is useful for general digestion of proteins.

Proteinase K Remains Active:

Over a wide pH range (optimal activity between 6.5 and 9.5)
Under denaturing conditions (e.g. the presence of SDS or urea)
In the presence of metal chelating agents (e.g. EDTA)
At comparatively high temperatures (optimum digestion temperature is 65°C)

Applications: Removal of endogenous nucleases during the preparation of DNA and RNA;

 preparation of tissue sections for in situ hybridization.

Performance and Quality Testing: Endodeoxyribonuclease and exodeoxyribonuclease assays;

 liquid form tested for absence of RNase activity.

Unit Definition: One mAnson unit is described as that amount of enzyme that liberates

 1 mole of Folin-positive amino acid within one minute at 37°C using hemoglobin as a substrate.