endoproteasas

Endoproteasas, or endopeptidases, are proteolytic enzymes that cleave peptide bonds within a polypeptide chain rather than at its termini. They generate shorter fragments and can activate precursor proteins (zymogens). This distinguishes them from exopeptidases, which remove amino acids from the N- or C- terminus.

Endoproteasas are classified by their catalytic mechanism into several main families. Serine proteases use a serine in the active site (examples include trypsin, chymotrypsin, elastase, and subtilisin). Cysteine proteases rely on a catalytic cysteine (e.g., papain, caspases). Aspartic proteases employ two aspartate residues (e.g., pepsin, retroviral proteases). Metalloproteases depend on a metal ion, typically zinc (e.g., matrix metalloproteinases, thermolysin). Each class has characteristic substrate specificities and active-site architectures that govern which peptide bonds are cleaved.

Biological roles of endoproteases are diverse. They participate in digestion (pepsin in the stomach; pancreatic trypsin and chymotrypsin in the small intestine), protein turnover, and the activation of many inactive precursors. They also contribute to immune processing and programmed cell death (for example, caspases in apoptosis and cathepsins in antigen processing). Dysregulation can be involved in diseases such as cancer metastasis, inflammatory disorders, and pancreatitis.

Applications of endoproteases span research and industry. In proteomics, trypsin and other proteases are used to digest proteins for sequencing and mass spectrometry. In medicine and biotechnology, protease inhibitors are used to regulate proteolysis (e.g., pepstatin for aspartic proteases, TIMPs for metalloproteases), and industrially, proteases are employed in detergent formulations and protein processing.