Biologically Active Content

Expression

Biologically Active Protein Content

mg

Absorbance Spectroscopy , Residual Porcine Pancreatic Elastase (PPE) Activity

20 mM Tris–HCl, 150 mM NaCl, 0.01% Tween-80

25 °C

8.0

None

405 nm

None

Protein samples (50 μl) were added into 100 μl of assay buffer followed by addition of 50 μl (3.0 μg/ml) PPE, incubation at 37 °C for 15 min and addition of 50 μl of 2 mM chromogenic substrate and further incubation for 2 h at 25 °C.

The activity of residual PPE was determined by measuring the release of p-nitroaniline from chromogenic substrate at 405 nm. Pure human α1-PI protein was used as reference standard for corresponding recombinant α1-PI concentration and residual PPE activity.