Proteinase K Solution (20 mg/mL), RNA grade

We recommend storing it at 4°C.

Scrape a single colony from the surface of an agar plate and transfer to 12 µL of SCL solution [10 mM Tris-HCl (pH 7.5), 1 mM EDTA, 50 µg/mL proteinase K] and incubate for 15 min at 55 degrees C. Inactivate proteinase K for 15 min at 80 degrees C and add 20 µL of deionized water. Centrifuge at 12,000 x g for 3 min. Transfer the supernatant to a new tube.

Concentration: Generally proteinase K is used in the concentration range of 50 to 500 µg/mL at 65 degrees C in the presence of SDS (0.5-1%).

Temperature optimum: 65 degrees C; 12X more active at 65 degrees C than at 25 degrees C.

pH: Proteinase K is stable over a wide pH range (4.0 to 12.5), with optimal activity at pH 6.5 to 9.5. It is most stable at pH 8.
Inactivation: Heat inactivate Proteinase K at 80 degrees C for 15 min. Phenol extraction is the recommended method to ensure complete inactivation.

Inhibited by: PMSF (0.1 to 1.0 mM of PMSF is usually sufficient for inhibition of Proteinase K)

Not inhibited by: Proteinase K is not inactivated by metal ions, chelating agents (e.g., EDTA), sulfhydryl reagents or by trypsin or chymotrypsin inhibitors. Activity can be stimulated by addition of denaturing agents (SDS and urea).