Defensin alpha 1B (human neutrophil peptide 1) (DEFA1B (HNP-1))

Defensin alpha 1B (human neutrophil peptide 1, DEFA1B) is a member of the alpha-defensin subfamily, encoding a small (32–36 amino acid), cationic, amphipathic peptide found abundantly in neutrophil granules and mucosal epithelia[1][3][5][6]. The protein contains three pairs of intramolecular disulfide bonds, forming an antiparallel beta-sheet structure stabilized by these bridges[1][4][5][6]. DEFA1B exerts rapid antimicrobial activity against bacteria, viruses, and fungi by disrupting plasma membranes, inhibiting bacterial cell wall synthesis (via lipid II binding), and modulating immune responses such as cytokine secretion and APC maturation[3][5]. Its expression is essential for innate immunity, and dysregulation may contribute to infectious, inflammatory, or malignant diseases[3][5]. DEFA1B and its paralogs (DEFA2/HNP-2, DEFA3/HNP-3) differ by a single amino acid and are subject to genetic copy number variation[1][3]. Key sequence and structure highlights: - Sequence: ACYCRIPACIAGERRYGTCIYQGRLWAFCC (HNP-1)[1] - Structure: Three-stranded beta-sheet, stabilized by three disulfide bonds, amphipathic globular protein[1][4][6] In summary: Defensin alpha 1B (DEFA1B), best known as human neutrophil peptide 1 (HNP-1), is a canonical antimicrobial effector of innate immunity with therapeutic potential in infection, inflammation, and possibly cancer. Its mechanism involves microbial membrane disruption and immune modulation. Therapeutic application faces safety and delivery challenges but remains an active area of translational research[3][5][6].

Other names

Human neutrophil peptide 1HNP-1DEFA1DEF1HP-1HP1Neutrophil defensin 1

Drugs targeting or mimicking DEFA1B may act through membrane disruption, direct microbicidal activity, immunomodulation (e.g., cytokine induction), or inhibition of viral entry/disassembly