Proteinase K is a highly reactive nonspecific serine protease that belongs to the subtilisin family of proteins. It cleaves at the carboxylic acid side of aliphatic, aromatic, or hydrophobic amino acids. Proteinase K is capable of inactivating RNases and DNases and is used in the isolation or preparation of high molecular weight nucleic acids. Proteinase K is also useful for helping to characterize enzymes, due to its cleavage specificity. This enzyme was designated proteinase K because of its ability to hydrolyze keratin. Proteinase K is stable in a wide variety of detergents and buffer salts and at various temperatures and pH. The isoelectric point of proteinase K is 8.9.

Proteinase K is typically used at a concentration of 50-100 μg/ml. It is active with or without the presence of SDS, urea, EDTA or various metal ions, but the activity of proteinase K can be increased by adding the denaturing agents and the structure of proteinase K can be stabilized by addition of Ca ²⁺. Proteinase K is inactivated by heating to 95°C for 10 minutes or using an inhibitor such as PMSF, AEBSF or DFP.

MW: 28.5 kDa

Activity: ≥30 U/mg

Unit Definition: One unit is defined as the amount of enzyme that will liberate 1.0 μmol tyrosine (Folin-positive amino acid) from casein per minute at 37°C, pH 7.5.

Source: Yeast cells with cloned gene encoding Engyodontium album (Tritirachium album) endolytic protease.
Storage/Handling: Store at -20°C.
Reconstitute in 50mM Tris-HCl (pH 8.0), 3mM CaCl2.