Proteolyzed

Proteolyzed is the past participle of proteolyze, meaning that a protein or peptide has undergone proteolysis, the cleavage of peptide bonds by proteases. In biology, proteolysis is a controlled, often essential process that converts precursor molecules into active forms, degrades damaged proteins, or generates peptide fragments for various functions. The term proteolyzed is used to describe proteins that have had peptide bonds selectively cleaved, producing smaller polypeptides or amino acids.

Proteolysis is catalyzed by proteases, including serine, cysteine, metalloproteases, and aspartic proteases. These enzymes can act as endopeptidases, cutting within a protein, or exopeptidases, trimming terminal amino acids. Proteolysis can be regulated by inhibitors, pH, localization, and co-factors, and may be part of signaling cascades or housekeeping turnover.

Biological roles include maturation of enzyme precursors (zymogens), activation of hormones (such as proinsulin to insulin), processing of receptor or signaling proteins, remodeling of extracellular matrix, and turnover of cytosolic proteins by the ubiquitin-proteasome system. In the immune system, proteolysis generates antigenic peptides presented by MHC class I molecules.

In research and medicine, detecting proteolyzed fragments informs about protease activity, disease states, or sample handling. Proteolyzed samples can occur during tissue extraction if proteases remain active, leading to artifactual cleavage unless inhibitors are used.