SOURCE. Human pancreas.
Chromatographically purified, salt-free, lyophilized.
Approximately 95% protein comprised of typsins and chymotrypsins.
MW - 25,000
Store at -20°C. Stable 9-12 months.
35-40 units per mg of protein.
One unit will hydrolyze 1 mg of casein-FITC (EPC No. CF433) in 10 minutes at pH 8.7 and 37°C.
Assay media is 2.0 ml 100 mM Tris pH 8.7 containing 10 mM CaCl2, 10 mg casein-FITC and 5-20 µg protease. After incubation at 37°C for 10 minutes, add 1 ml 10% TCA. Centrifuge approximately 15,000 gr, add 0.5 ml clarified supernatant to 2 ml Tris pH 8.7 buffer.
Read A495 nm. Determine specific activity from 1 mg/ml casein-FITC totally hydrolyzed with excess protease (ca. 0.1mg) by the same procedure. Generally 1mg/2.5 ml hydrolyzed casein-FITC has A495 of .09 to 0.12.