<unk>  from animals, plants and fungi organised by their secondary structure content. Circle size indicates overall molecular weight of each<unk> <unk>  are a unique and diverse group of molecules, which are divided into subgroups on the basis of their amino acid composition and structure.<unk>  are generally between 12 and 50 amino acids. These<unk>  include two or more positively charged residues provided by arginine, lysine or, in acidic environments, histidine, and a large proportion (generally >50%) of hydrophobic residues. The secondary structures of these molecules follow 4 themes, including i) α-helical, ii) β-stranded due to the presence of 2 or more disulfide bonds, iii) β-hairpin or loop due to the presence of a single disulfide bond and/or cyclization of the<unk> chain, and iv) extended. Many of these<unk>  are unstructured in free solution, and fold into their final configuration upon partitioning into biological membranes. It contains hydrophilic amino acid residues aligned along one side and hydrophobic amino acid residues aligned along the opposite side of a helical molecule. This amphipathicity of the<unk>  allows them to partition into the membrane lipid bilayer. The ability to associate with membranes is a definitive feature of<unk> , although membrane permeabilization is not necessary. These<unk>  have a variety of<unk>  activities ranging from membrane permeabilization to action on a range of cytoplasmic targets. Type characteristic<unk>  Anionic<unk>  rich in glutamic and aspartic acids Maximin H5 from amphibians, Dermicidin from humans Linear cationic α-helical<unk>  lack in cysteine Cecropins, andropin, moricin, ceratotoxin and melittin from insects, Magainin, dermaseptin, bombinin, brevinin-1, esculentins and buforin II from amphibians, CAP18 from rabbits, LL37 from humans Cationic<unk> enriched for specific amino acid rich in proline, arginine, phenylalanine, glycine, tryptophan abaecin and drosocin, apidaecin, diptericin, and attacin from insects, prophenin from pigs, indolicidin from cattle. Anionic/cationic<unk>  forming disulfide bonds contain 1~3 disulfide bond * 1 bond: brevinins; * 2 bonds: protegrin from pig, tachyplesins from horseshoe crabs; * 3 bonds: defensins from humans; * more than 3: drosomycin in fruit flies
Antimicrobial peptides
Neurotoxin
Insect toxin
Immunotoxin
Bacterial adhesin
Lectin
Staphylotoxin
Alpha-neurotoxin