Defensins [1,2,3,4,5], also known as α-defensins, are a family of
structurally related cysteine-rich peptides active against many Gram-negative
and Gram-positive bacteria, fungi, and enveloped viruses. Some defensins are
also called corticostatins (CS) because they inhibit corticotropin-stimulated
corticosteroid production. Defensins kills cells by forming voltage-regulated
multimeric channels in the susceptible cell's membrane. They play a
significant role in innate immunity to infection and neoplasia. The peptides
known to belong to this family are listed below.
Rabbit defensins and corticostatins: CS-I (NP-3A), CS-II (NP-3B), CS-III
(MCP-1), CS-IV (MCP-2), NP-4, and NP-5.
Guinea-pig neutrophil defensin (GPNP).
Human neutrophil defensins 1 to 4 and intestinal defensins 5 and 6.
Mouse small bowel cryptdins 1 to 5.
Rat NP-1 to NP-4.
All these peptides range in length from 29 to 35 amino acids. There are seven
invariant residues, including six cysteines all involved in intrachain
disulfide bonds. A schematic representation of peptides from the defensin
family is shown below.
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