Defensins are a large family of broad-spectrum antimicrobial peptides, identified originally in leukocytes of rabbits and humans.
Defensins, cationic/polar peptides (30-35 aa; 3-4kD), are distinguished by a conserved tri-disulfides and a largely b-sheet structure.
In leukocytes, these peptides are stored in cytoplasmic granules and are released into phagolysosomes where they contribute to the killing of engulfed microorganisms.
Defensins are classified into two families designated alpha and beta based on distinctive, although similar, tri-disulfide linkages in the peptides.
b-defensins are slightly larger and differ in the position and arrangement of 3 disulfides.
In humans, six a-defensin (cryptidins), HD 1-6 (HD1-4 are also known as HNP1-4 for Human Neutrophil Peptides), and two b-defensins, HBD-1 and HBD-2, have been identified.
Alpha-defensins are encoded by genes designated DEFA1-6, whereas human b-defensins are encoded by the DEFB1 and DEFb2 genes.
HD1-4 are expressed in neutrophils, whereas HD5 and HD6 are expressed in epithelial cells of the intestinal and reproductive tract.
HD1-3/HNP1-3 make up about 30% of the neutrophil's total granule protein.
The HNPs are 29 to 30 amino acids long and are identical in sequence except at the N-terminal amino acid.
Applications:Suitable for use in ELISA, Neutralization and Western Blot.
