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proteasesZoomA-Z

Subject - Biochemistry

Proteases are enzymes that can hydrolytically break down other enzymes, proteins, and polypeptides (digestion). Other terms used for this class of enzymes include peptidases (abbreviation of peptide bond hydrolases), proteinases, or simply proteolytic enzymes.

Depending on the point of attack used by the proteases, they are classified as either exoproteases or endoproteases. Exoproteases (from Greek exo, “outside”) attack the peptide chain at the ends and typically remove a single amino acid, or sometimes a di- or tripeptide, from the end of the peptide chain. The exoproteolytic removal of amino acids can occur at either the N- or C-terminus of the protein, so exoproteases are subdivided into N-terminal or C-terminal exoproteases. Hydrolytic splitting in the middle of the chain is catalyzed by endoproteases.

Proteases are extremely important proteins for metabolism. Intracellular proteases degrade damaged or excess peptides within a cell and are essential for the transport of peptides to their active site (splitting of signal peptides from membrane proteins or exported proteins by membrane-dwelling proteases). Extracellular proteases take care of food digestion or the activation of the blood-clotting system, the complement system, and the fibrinolytic system of the body.