Figure 3. Simplified schematic representation of kallikrein-kinin system regulation.

Kininogen is cleaved by kininogenases, such as tissue kallikrein, to generate active kinins. Kallistatin and bikunin are specific inhibitors of tissue kallikrein. Carboxypeptidases, such as carboxypeptidase B2, can cleave C-terminal arginine or lysine residues from active kinins, i.e. bradikinin, to inactivate them thereby regulating their activities.