Proteolysis in neuropeptide processing

The paper reviews the functions of proteolytic enzymes in processing intracellular peptides. The enzymes may "activate" precursors of active peptides, "inactivate" active peptides by their degradation to biologically inactive forms, and "change" the peptides degrading biologically active forms to smaller peptides of different biological activity. The results of own studies on angiotensin II and its fragments are quoted to illustrate how various fragments of the peptide may display various biological activity.