Trypsin hydrolyzes peptides, amides, and ester bonds involving the carboxyl groups of L-arginine or L-lysine. Increased serum values of this enzyme and/or its zymogen (trypsinogen) have been found in patients with cystic fibrosis. Trypsinogen has three isoforms: cationic (trypsinogen 1), anionic (trypsinogen 2, MW - 22.5 kDa), and mesotrypsinogen (trypsinogen 3, MW - 25 kDa).