SNAP-8 is an acetylated eight residue peptide modelled on the N-terminal end of SNAP-25, one of the three proteins that form the SNARE complex driving vesicle fusion at the neuromuscular junction. It is an extension of the earlier hexapeptide argireline, adding two residues to the same competitive premise. Work on the compound sits at the boundary between vesicle trafficking biochemistry and topical formulation science.
Key facts
| Type | Acetylated synthetic octapeptide, SNAP-25 N-terminal mimetic |
| Amino acid count | 8 |
| Sequence | Ac-Glu-Glu-Met-Gln-Arg-Arg-Ala-Asp-NH2 |
| Molecular formula | C41H70N16O16S |
| Molecular weight | 1075.2 g/mol |
| CAS number | 868844-74-0 |
| Terminal modifications | N-terminal acetyl, C-terminal amide |
| Synonyms | Acetyl octapeptide-3, acetyl glutamyl heptapeptide-1, acetyl octapeptide-1 |
Structure and chemistry
The peptide is built by solid phase synthesis on an amide resin, acetylated at the N-terminus while still on solid support, then cleaved and purified by reversed phase HPLC. Both termini are capped, which removes the charged amine and carboxylate of a free peptide and leaves a molecule with a net negative charge carried by the two glutamates and the aspartate against two arginines.
The methionine at position three is the analytical weak point. Methionine oxidises to the sulfoxide on exposure to air, peroxides in excipients or trace metal ions, adding sixteen mass units and producing a peak that elutes earlier on reversed phase. A certificate that reports purity without separating the sulfoxide understates the degradation present, and material that has been stored in solution at room temperature will show it. Mass spectrometry that resolves the 1075 and 1091 species is the check worth asking for.
SNAP-8 is freely soluble in water at working concentrations, which distinguishes it from most eight residue sequences and follows from its charged, capped composition. In cosmetic formulation it is normally supplied as a dilute aqueous solution with a preservative system and not as the neat lyophilised peptide, and the concentration on such a label refers to the solution and not to peptide content.
Mechanism of action
Vesicle fusion at the synapse requires the assembly of a four helix bundle from syntaxin-1, VAMP and SNAP-25, which contributes two helices. Assembly of that bundle pulls the vesicle and plasma membranes together and drives fusion. The N-terminal region of SNAP-25 is one of the contacts that positions the complex, and the premise behind SNAP-8 is competition: a free peptide reproducing that sequence occupies the interface and slows productive bundle formation.
Evidence for the mechanism is drawn mainly from in vitro assembly assays and from catecholamine release measurements in chromaffin cell culture, where the peptide reduces evoked exocytosis at high micromolar to millimolar concentration. Affinity is low, consistent with a short linear peptide competing against a folded coiled-coil interaction, and the concentrations required are far above those reached by passive diffusion across intact stratum corneum. Penetration, not intrinsic activity, is the limiting variable in most reported work, and formulation studies dominate the literature for that reason.
Research applications
- In vitro SNARE assembly assays measuring competition against SNAP-25 N-terminal binding.
- Chromaffin cell culture quantifying evoked catecholamine release as a functional readout of exocytosis.
- Keratinocyte and reconstructed epidermis models assessing peptide penetration across a stratum corneum barrier.
- Methionine oxidation studies tracking sulfoxide formation by LC-MS under thermal and oxidative stress.
- Formulation stability work in aqueous and emulsion systems, including preservative compatibility.
- Comparative assays against the hexapeptide argireline to test whether the two additional residues change competition.
Compounds studied in neuronal signalling sit in NuVion’s Neuroscience category.
Handling in the laboratory
Lyophilised peptide is reconstituted with bacteriostatic water added slowly down the wall of the vial and swirled. The reconstitution calculator converts vial content and diluent volume into a stock concentration. Solubility is not the constraint here; oxidation is, so stock is prepared in degassed water where the work allows it and held in tightly closed vials with minimal headspace.
Methionine-containing peptides are kept away from peroxide-bearing excipients, from copper and iron traces and from prolonged light exposure. Aliquoting at first reconstitution matters more than usual, since every reopening exposes the stock to fresh air. Where an assay runs over days, a fresh aliquot each day gives more consistent results than drawing repeatedly from one tube, and any unexplained loss of activity in this compound is worth checking by mass spectrometry for the plus sixteen species before other explanations are pursued.
Testing and supply from NuVion
NuVion supplies a tested range across neuronal signalling, including Semax, Selank and Pinealon, and a skin and matrix range led by GHK-Cu. That range is manufactured at a GMP-audited facility and independently tested by Janoshik Analytical, with purity determined by RP-HPLC and identity confirmed by mass spectrometry, and the certificates are published in the Certificate of Analysis library. SNAP-8 is not part of the current catalogue and this page is a reference profile.
Related compounds
For matrix and keratinocyte work the copper tripeptide GHK-Cu is the most studied comparator in this library. Other short neuroactive peptides include Semax and Selank, both ACTH and tuftsin derived fragments, and Pinealon among the short bioregulator sequences. Background on capped termini and synthesis chemistry is covered in peptide synthesis.
Frequently asked questions
What is the difference between SNAP-8 and argireline?
Argireline is acetyl hexapeptide-8, a six residue acetylated peptide from the same region of SNAP-25. SNAP-8 extends the sequence to eight residues with the same acetyl and amide capping. The competitive premise is identical and reported potency differences between the two are modest and formulation dependent.
Why does the molecular weight sometimes read 1091 instead of 1075?
Because the methionine at position three has oxidised to the sulfoxide, which adds sixteen mass units. It is the most common degradation product for this sequence and it appears in material stored in solution, exposed to air or formulated alongside peroxide-bearing excipients. Analysis that separates the two species is the way to quantify how much is present.
Is SNAP-8 related to botulinum toxin?
They act on the same machinery from different directions and are not otherwise related. Botulinum neurotoxin is a bacterial protease that cleaves SNAP-25 enzymatically and irreversibly. SNAP-8 is a short synthetic peptide proposed to compete for a protein interface without cleaving anything, with low affinity and full reversibility.
Is SNAP-8 listed in the Australian Register of Therapeutic Goods?
No. SNAP-8 is not included in the Australian Register of Therapeutic Goods and has not been assessed by the Therapeutic Goods Administration for quality, safety or efficacy. Material of this class is supplied in Australia as a laboratory chemical for in vitro research.
Research use only. The compound described on this page is discussed as a laboratory chemical used in in vitro research. It is not included in the Australian Register of Therapeutic Goods and has not been assessed by the Therapeutic Goods Administration for quality, safety or efficacy. It is not for human or veterinary use, and nothing on this page is a representation about therapeutic use.
