Serine Proteinases: Overview☆

Serine proteinases are a family of enzymes with a serine residue at their active site and include neutrophil elastase, cathespin G, proteinase 3, plasminogen activators, granzymes, and type II transmembrane serine proteinases. Serine proteinases cleave various extracellular proteins to contribute to tissue remodeling, inflammation, and host defense against bacteria. However, when their activity is excessive or prolonged, serine proteinases also contribute to the pathogenesis of chronic obstructive pulmonary disease, cystic fibrosis, acute lung injury, pulmonary fibrosis, and respiratory viral infections. Serine proteinases also cleave proteins expressed by influenza viruses and coronaviruses to promote viral entry into cells and viral pathogenicity.