Peptide Classifications Explained
Common classification schemes used to organise peptides by source, structure, and function in research literature.
Last updated: 21 April 2026
Classification by function
Peptides studied in research are often grouped by their investigated biological roles: hormonal (insulin-like), growth-modulating, metabolic-pathway-targeting, immune-modulating, neuropeptide-class, and antimicrobial classes.
This functional classification helps researchers find related peptides and understand the body systems being studied.
Classification by origin
Endogenous peptides occur naturally in the body. Exogenous peptides are introduced from outside (food, supplements, medicines). In research contexts, most studied peptides are either endogenous sequences synthesised artificially, or novel variants designed in the lab.
Classification by structure
Linear peptides have a single unbranched chain. Cyclic peptides have their ends joined together, which can confer stability. Branched peptides have side-chain attachments. Each structural type may have different synthesis, stability, and activity profiles.
Therapeutic vs cosmetic peptides
Therapeutic peptides are those studied for systemic effects on health (hormonal, metabolic, immune). Cosmetic peptides are researched for local skin effects. This distinction affects both the research literature and regulatory classification.
Regulatory classification
In Australia, some peptides fall into scheduled substance classes (e.g. growth-hormone-related peptides under Schedule 4 of the Poisons Standard). This classification affects legal supply channels and prescription requirements.