Figure 3.

The Kallikrein–Kinin/Bradykinin System. Kallikrein serine proteases cleave kininogens to release the vasoactive peptides bradykinin (BK) and kallidin (KD). The peptidase Kininase I (carboxypeptidase M, CPM) further cleaves BK and KD into the active des-Arg⁹-bradykinin (DABK) and des-Arg¹⁰-kallidin (DAKD). Kininase II or ACE, inactivates the KKS by degrading BK, KD, DABK and DAKD into inactive metabolites. Similarly, ACE2 metabolizes DABK to BK (1-7) and DAKD to KD (1-8) [79] (created with Biorender.com).