A fluorometric determination of trypsin-like amidase activity and activity of trypsin inhibitors in serum.

The activity of crystalline trypsin and the trypsin-like amidase activity and the activity of trypsin inhibitors in serum were measured fluorometically, with a-benzoyl--L-arginine--na phthylamide (BANA) as substrate. The method is simpler and more sensitive than the colorimetric method based on the Bratton-Marshall reaction. Serum of pancreatectomized dogs hydrolyzed BANA at a significant rate, which suggests that serum amidases other than trypsin are active in this determination.