S1A serine protease (S1A)

S1A serine proteases comprise a well-studied group of enzymes that cleave peptide bonds in proteins, relying on a catalytic triad including serine in the active site[3][7]. The family’s prototypical members—trypsin, chymotrypsin, and elastase—are central to extracellular protein breakdown in the digestive tract, but other S1A proteases function in coagulation (e.g., thrombin, factor Xa), immune surveillance (e.g., granzymes), inflammation (e.g., kallikreins), and membrane-associated signaling (e.g., matriptase)[1][2][4]. They are synthesized as inactive zymogens and activated by proteolytic cleavage in response to physiological stimuli; their dysregulation is implicated in cancer, thrombotic events, and immune diseases[1][2][4][7]. Drug discovery efforts target this family using small molecule inhibitors to block pathological proteolysis, though therapeutic use must balance efficacy with bleeding and immunosuppressive risks[7].

Other names

trypsin-like serine proteasetrypsin subfamilyClan PA S1A proteaseclassic serine protease

Protease inhibition (competitive and irreversible inhibition of the catalytic site); Zymogen activation or blocking via cofactors; Substrate cleavage prevention