oligopeptide

An oligopeptide is a short chain of amino acids linked by peptide bonds. In protein science, the term distinguishes short peptides from longer polypeptides and proteins. Dipeptides and tripeptides contain two and three amino acids, while oligopeptides generally encompass several to a few dozen residues; many sources set the upper limit around 20 amino acids, though definitions vary.

Biogenesis and synthesis: Oligopeptides can be generated by proteolytic processing of larger precursor proteins or produced directly by chemical or solid-phase synthesis. They may be produced in vivo by enzymes that trim or modify larger proteins, or prepared for research and therapeutic use by automated synthesis.

Examples and roles: Many biologically active oligopeptides function as hormones or signaling molecules. Vasopressin and oxytocin are nonapeptides that regulate fluid balance and social behaviors. Other oligopeptides participate in antimicrobial defense, immune signaling, or act as receptor ligands. Short peptides also serve as drug leads and diagnostic tools.

Detection, properties, and applications: Oligopeptides are analyzed by chromatography and mass spectrometry, and their sequences are determined by sequencing methods such as Edman degradation or MS-based approaches. They generally have lower structural complexity than long polypeptides, though their activity can be influenced by conformation and post-translational modifications. Oligopeptides find uses in basic research, medicine as peptide-based therapeutics, and as components in diagnostics and biotechnology.