Plasma serine protease

Plasma serine proteases are a large and diverse family of enzymes that cleave peptide bonds in proteins, defined by a catalytic triad of serine, histidine, and aspartate residues in their active site[1][5]. They are ubiquitously expressed and play critical roles in essential physiological processes, including digestion (e.g., trypsin, chymotrypsin, elastase), blood coagulation and fibrinolysis (e.g., thrombin, plasmin, factors X, XI, XII), complement activation (e.g., C1r, C1s, MASP-2), and the kallikrein-kinin system (e.g., plasma kallikrein)[1][6]. These proteases are often synthesized as inactive zymogens and activated by proteolytic cleavage, forming cascades that amplify biological signals[2]. Their activity is tightly regulated by endogenous inhibitors, notably serpins, which irreversibly inactivate specific proteases by forming covalent complexes[1]. Dysregulation of plasma serine proteases is implicated in a wide range of diseases, including bleeding and thrombotic disorders, complement deficiencies, inflammatory conditions, and cancer[1][2][5]. Several plasma serine proteases are established therapeutic targets, with drugs developed to modulate their activity for the treatment of thrombosis, hereditary angioedema, and other conditions[1]. Biomarkers based on plasma serine protease activity or levels are used diagnostically in coagulation disorders, pancreatic function assessment, and cancer screening[5].

Other names

Serine proteaseSerine endopeptidaseClotting factor (for coagulation system members)Complement factor (for complement system members)Pancreatic protease (for digestive enzymes)KallikreinMannan-binding lectin-associated serine protease (MASP)TrypsinChymotrypsinElastaseThrombinPlasmin

Inhibition of catalytic activity (competitive or allosteric), Zymogen activation, Substrate cleavage prevention, Covalent inactivation (serpin mechanism)[1]