Human neutrophil peptide 3 (HNP-3)

Also known as HNP-3; human α-defensin 3

A neutrophil α-defensin distinguished by N-terminal aspartate, enabling sequence-matched studies of charge and membrane interactions.

Length: 30 amino acids
Half-life: Not well characterised
Mechanism: HNP-3 interacts with microbial envelopes through a folded α-defensin surface, with membrane permeabilisation contributing to activity in laboratory systems. No single established receptor explains its effects, and its N-terminal aspartate changes its electrostatic properties relative to HNP-1.
Studied in: Bacterial and fungal assays, membrane models and structural comparisons investigate the influence of HNP-3 charge, folding and oligomerisation on microbial interactions.

About Human neutrophil peptide 3 (HNP-3)

HNP-3 is a 30-amino-acid α-defensin encoded by DEFA3 and stored in human neutrophil azurophilic granules. It was characterised alongside other neutrophil defensins during the 1980s. The mature sequence differs from HNP-1 only at the first residue: aspartate replaces alanine. This substitution introduces an additional acidic side chain while retaining the same six cysteines and shared defensin core. Precursor processing is required to generate the mature peptide found in granules.

Crystallographic work on HNP-3 helped establish the compact β-sheet architecture and dimeric organisation associated with human neutrophil α-defensins. Its three disulphide bonds follow the canonical Cys I–VI, II–IV and III–V connectivity. Comparisons with HNP-1 allow researchers to examine an N-terminal charge change without altering the remainder of the sequence. Nevertheless, relative activity is assay-dependent: ionic strength, membrane composition and microbial strain can all influence the apparent consequences of this single-residue difference.

Laboratory notes

Check that the supplied sequence begins with aspartate; HNP-1 and HNP-3 differ by only this N-terminal residue.
Use an appropriate structural or chromatographic method alongside mass analysis to assess folding and sample homogeneity.
When comparing membrane interactions, keep pH and ionic strength constant to separate sequence effects from buffer-dependent electrostatics.

Storage and reconstitution basics: storage guide.

Questions about Human neutrophil peptide 3 (HNP-3)

What makes HNP-3 chemically distinct from HNP-1?

Its N-terminal aspartate replaces the alanine in HNP-1. The acidic side chain changes charge characteristics without changing the remaining sequence.

Is HNP-3 necessarily less active than HNP-1?

No universal ranking is justified. Relative activity depends on the organism, assay medium, folding state and measured endpoint.

Why is HNP-3 useful in structural research?

Its experimentally characterised α-defensin fold and close sequence relationship to HNP-1 support controlled studies of charge, dimerisation and membrane association. HNP-3 is for research use only.

Is Human neutrophil peptide 3 (HNP-3) for human use?

No. It is supplied strictly for in-vitro laboratory research and is not for human or animal consumption.

Related research peptides

All products are sold for laboratory research use only. Not for human consumption, not a medicine, not for diagnosing, treating or preventing any condition.