Antimicrobial peptides

Defensins are small cysteine-rich cationic proteins across cellular life, including vertebrate and invertebrate animals, plants, and fungi. They are host defense peptides, with members displaying either direct antimicrobial activity, immune signaling activities, or both. They are variously active against bacteria, fungi and many enveloped and nonenveloped viruses. They are typically 18-45 amino acids in length, with three or four highly conserved disulphide bonds.

class of peptides that have antimicrobial activity

Melittin is the main component (40–60% of the dry weight) and the major pain-producing substance of honeybee (Apis mellifera) venom. Melittin is a basic peptide consisting of 26 amino acids.

Gramicidin, also called gramicidin D, is a mix of ionophoric antibiotics, gramicidin A, B and C, which make up about 80%, 5%, and 15% of the mix, respectively. Each has 2 isoforms, so the mix has 6 different types of gramicidin molecules. They can be extracted from Brevibacillus brevis soil bacteria. Gramicidins are linear peptides with 15 amino acids. This is in contrast to unrelated gramicidin S, which is a cyclic peptide.

Bacteriocins are proteinaceous or peptidic toxins produced by bacteria to inhibit the growth of similar or closely related bacterial strain(s). They are similar to yeast and paramecium killing factors, and are structurally, functionally, and ecologically diverse. Applications of bacteriocins are being tested to assess their application as narrow-spectrum antibiotics.

class of antibiotic drugs

Fusafungine (INN), also known as fusafungin, is an active agent used in antibiotics for treatment of nasal and throat infection. It also possesses anti-inflammatory properties. Fusafungine is a mixture of enniatin cyclohexadepsipeptides made up of alternating D-α-hydroxyvaleric acid and L-N-methylamino acid residues, produced by the ascomycete Fusarium lateritium, and marketed by Servier under the trade names Locabiotal, Bioparox, and Locabiosol.

A colicin is a type of bacteriocin produced by and toxic to some strains of Escherichia coli. Colicins are released into the environment to reduce competition from other bacterial strains. Colicins bind to outer membrane receptors, using them to translocate to the cytoplasm or cytoplasmic membrane, where they exert their cytotoxic effect, including depolarisation of the cytoplasmic membrane, DNase activity, RNase activity, or inhibition of murein synthesis.

Malacidins are a class of chemicals made by bacteria found in soil that can kill Gram-positive bacteria. Their activity appears to be dependent on calcium. The discovery of malacidins was published in 2018.

Reuterin (3-hydroxypropionaldehyde) is the organic compound with the formula HOCH2CH2CHO. It is a bifunctional molecule, containing both a hydroxy and aldehyde functional groups.

Dermcidin is a protein with 110 amino acids that in humans is encoded by the DCD gene. The full-length protein produces derived peptides as proteolysis-inducing factor (PIF) and other anti-microbial peptides, secreted by human eccrine sweat glands onto the skin as a part of the innate host defense of the immune system. PIF is involved in muscular proteolysis.

Histatins are histidine-rich (cationic) antimicrobial proteins found in saliva. Histatin's involvement in antimicrobial activities makes histatin part of the innate immune system. Histatin was first discovered (isolated) in 1988, with functions that are responsible in keeping homeostasis inside the oral cavity, helping in the formation of pellicles, and assist in bonding of metal ions.

Alamethicin is a channel-forming peptide antibiotic, produced by the fungus Trichoderma viride. It belongs to peptaibol peptides which contain the non-proteinogenic amino acid residue Aib (2-aminoisobutyric acid). This residue strongly induces formation of alpha-helical structure. The peptide sequence is

thumb | right Lysostaphin (, glycyl-glycine endopeptidase) is a Staphylococcus simulans metalloendopeptidase (crystal structure of lysostaphin). It can function as a bacteriocin (antimicrobial) against Staphylococcus aureus.

protein-coding gene in the species Homo sapiens

protein-coding gene in the species Homo sapiens

Lugdunin is an investigational antibiotic, classified as a thiazolidine-containing cyclic peptide. It was isolated in 2016 after Staphylococcus lugdunensis was identified as the species of bacteria from the human nose that suppressed growth of species of disease-causing bacteria in that part of the human microbiome.

Cecropins are antimicrobial peptides. They were first isolated from the hemolymph of Hyalophora cecropia, whence the term cecropin was derived. Cecropins lyse bacterial cell membranes; they also inhibit proline uptake and cause leaky membranes.

Thionins are a family of small proteins found solely in higher plants. Typically, a thionin consists of 45–48 amino acid residues. 6–8 of these are cysteine forming 3–4 disulfide bonds. They include phoratoxins and viscotoxins.