Welcome to the APD, the original antimicrobial peptide database, first online in 2003. As of Jan 1, 2026, the APD6 contained 6309 peptides, including 3379 natural antimicrobial peptides (AMPs), 2290 synthetic AMPs, and 373 predicted AMPs (mainly by AI). Natural AMPs with known sequences and activities cover the six life kingdoms (430 bacteriocins from bacteria, 5 from archaea, 8 from protists, 29 from fungi, 272 from plants, and 2628 from animals. The wheel of function of the APD6 records the following peptide functions/activities:

Antibacterial peptides Antibiofilm peptides Anti-MRSA peptides Anti-TB peptides Anti-endotoxin peptides Anti-toxin peptides Antiviral peptides Anti-HIV peptides Antifungal peptides Anti-Candida peptides Antiparasitic peptides Antimalarial peptides Anticancer peptides Anti-diabetic peptides Wound healing peptides Chemotactic peptides Anti-inflammatory peptides Spermicidal peptides Insecticidal peptides Ion channel inhibitors Protease inhibitors Antioxidant peptides Nematocidal peptides Bacteria-agglutinating peptides Synergistic peptides

Host defense animal peptides (76% of natural peptides): 1810 vertebrate and 818 invertebrate AMPs with known activity. There are 156 human AMPs, 408 biologically active peptides from mammals, 1113 membrane active peptides from amphibians (1034 from frogs and 71 from toads), 163 fish innate immune peptides, 55 reptile peptides, 48 from birds, 696 from arthropods, [410 from insects, 78 from crustaceans, 7 from myriapods, 201 from chelicerata, (46 from spiders, 103 from scorpions)], 54 from molluscs, 6 AMPs from protozoa, and more.

Experiment-determined 3D structures: The 542 unique structures in the APD6 have been unified into four classes (see typical structures above): (1) α-helix: top left: Amphibian magainin II; (2) β-sheet, top right bovine lactoferricin; (3) αβ structure: bottom left: plant-PsD1; (4) non-αβ structure: bottom right: bovine indolicidin.

A powerful database search engine for natural, synthetic, and predicted AMPs: You can search for peptide info using APD ID, peptide name, source organism, life domain/kingdom, peptide family name, amino acid sequence, peptide motif, length, charge, hydrophobic content, chemical modification, PDB ID, 3D structure, structural methods (e.g., NMR), antimicrobial activity, synergistic effects, target microbes, molecular targets, mechanism of action, contributing authors, and year of publication.

The novel antimicrobial peptide information pipeline (AMPIP) for R&D: AMPIP is aimed to facilitate the development of advanced AI predictors for more robust peptide antibiotics. You can go to the APD search interface. Then enter any search term (e.g., antimicrobial robustness, resistance development, peptide stability, in vivo PK, in vitro toxicity, in vivo toxicity, animal model, recombinant production, or clinical trials) in the "Additional information" followed by clicking on "Search". For additional details, please refer to the APD6 paper below.

Acknowledgement: The APD appreciates the consistent support of the Department of Pathology, Microbiology, and Immunology, UNMC as well as all users around the world.

CITE:

APD paper links: APD, APD2, APD3; APD4; APD5; APD6
[1] Wang, G., Schmidt, C., Li, X. and Wang, Z. (2026) APD6: The antimicrobial peptide database is expanded to promote research and development by deploying an unprecedented information pipeline. Nucleic Acids Research 54, D363-D374.
[2] Wang, G., Li, X. and Wang, Z. (2016) APD3: the antimicrobial peptide database as a tool for research and education. Nucleic Acids Research 44, D1087-D1093.
[3] Wang, Z. and Wang, G. (2004) APD: the antimicrobial peptide database. Nucleic Acids Research 32, D590-D592.

Last updated: Jan 2026 | Copyright 2003-present Dept of Pathology, Microbiology & Immunology, UNMC, All Rights Reserved

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