Snap-8 is a synthetic eight-residue peptide, Ac-Glu-Glu-Met-Gln-Arg-Arg-Ala-Asp-NH2, whose cosmetic-ingredient (INCI) name is Acetyl Octapeptide-3. Its sequence is an exact copy of residues 12 to 19 of human SNAP-25, one of the three proteins that form the SNARE complex behind vesicle fusion and neurotransmitter release. It is a two-residue extension of the better-known hexapeptide Argireline, and like Argireline it was designed to compete with SNAP-25 during SNARE complex assembly.
This profile sets out what can be verified about the molecule: its identity and nomenclature, the protein segment it mimics, how that segment fits into the SNARE machinery, how Snap-8 relates to its shorter predecessor, how thin the independent literature on it is, and what its sequence means for handling in the lab.
Identity at a glance
The values below are from the PubChem record for the peptide (CID 76283482). The INCI name is from the European Commission's CosIng inventory.
| Property | Value |
|---|---|
| Common name | Snap-8 (also written SNAP-8) |
| INCI name (EU CosIng) | Acetyl Octapeptide-3 |
| Other names in PubChem | Acetyl Glutamyl Heptapeptide-3 |
| Sequence (three-letter) | Ac-Glu-Glu-Met-Gln-Arg-Arg-Ala-Asp-NH2 |
| Sequence (one-letter) | Ac-EEMQRRAD-NH2 |
| Length | 8 residues, linear |
| Termini | N-terminal acetyl group, C-terminal amide |
| Molecular formula | C41H70N16O16S |
| Molecular weight | 1075.2 g/mol |
| CAS number | 868844-74-0 |
| PubChem CID | 76283482 |
| Parent protein | SNAP-25, residues 12 to 19 (UniProt P60880) |
The naming deserves a note, because it causes confusion. CosIng lists Acetyl Octapeptide-3, described as the reaction product of acetic acid and Octapeptide-3, with its functions recorded as humectant and skin conditioning. Those are nomenclature and function categories in an ingredient inventory, not findings about any effect. PubChem also lists "Acetyl Glutamyl Heptapeptide-3" as a synonym for the same structure, a name that counts the acetylated glutamate separately from the seven residues that follow. Searching CosIng for that name returns no entry, so Acetyl Octapeptide-3 is the name to use when matching an ingredient list or a regulatory record.
The sequence, residue by residue
Reading the sequence closely tells you most of what you need to know about the molecule's chemistry. For a primer on residues, termini and how peptide bonds join them, see what peptides are and the post on the peptide bond.
- Charge. There are three acidic side chains (Glu1, Glu2 and Asp8) and two basic ones (Arg5 and Arg6). The N-terminal acetyl group and the C-terminal amide remove the terminal charges that a free peptide would carry. At neutral pH the net charge is therefore about −1.
- Capped termini. Acetylation and amidation make the ends resemble the interior of a protein chain rather than a free peptide, which suits a fragment meant to mimic part of a larger protein. Capping also removes the free amine and carboxylate that exopeptidases recognize.
- One methionine. Met3 is the most oxidation-prone residue in the molecule. Oxidation to methionine sulfoxide adds 16 Da and is the first impurity to look for in an aged sample.
- One glutamine. Gln4 can deamidate slowly in solution, adding about 1 Da and introducing a negative charge.
- No cysteine, tryptophan or tyrosine. There are no disulfides to form or scramble, and the peptide has little absorbance at 280 nm, so concentration is better set by mass or by absorbance near 214 nm than by A280.
SNAP-25 and the SNARE complex
SNAP-25 (synaptosomal-associated protein of 25 kDa) is a 206-residue protein anchored to the inner face of the plasma membrane of neurons and neuroendocrine cells by palmitoyl groups on a cluster of cysteines near its middle. UniProt describes it as a t-SNARE involved in the regulation of neurotransmitter release.
Vesicle fusion depends on three SNARE proteins zipping together into a parallel four-helix bundle. Syntaxin-1 contributes one helix, the vesicle protein VAMP2 (synaptobrevin) contributes one, and SNAP-25 contributes two, one from each of its two SNARE motifs. Zippering from the membrane-distal end toward the membranes pulls the vesicle and plasma membranes together and drives fusion.
Where Snap-8 fits in that structure is specific. UniProt places the first SNARE motif of SNAP-25 at residues 19 to 81, within a disordered N-terminal stretch that runs from residue 1 to 23. The Snap-8 sequence, residues 12 to 19, therefore sits at the N-terminal edge of the first SNARE motif, the part of SNAP-25 at the membrane-distal end of the bundle where zippering begins. The design idea is that a free copy of that segment can compete with the native protein during early assembly and destabilize the complex.
It helps to compare this with botulinum neurotoxin type A, which is often invoked alongside these peptides. BoNT/A is a protease. UniProt records that it cleaves SNAP-25 between residues 197 and 198, near the C-terminal end of the second SNARE motif, permanently removing nine residues from the protein. Snap-8 does nothing of the kind. It copies a segment from the opposite end of SNAP-25, cleaves nothing, and acts, if at all, by competition, which would be reversible and concentration-dependent.
| Feature | SNAP-25 (native) | Argireline | Snap-8 | BoNT/A |
|---|---|---|---|---|
| What it is | 206-residue t-SNARE protein | Synthetic hexapeptide | Synthetic octapeptide | Bacterial zinc protease |
| Sequence | Full protein | Ac-EEMQRR-NH2 | Ac-EEMQRRAD-NH2 | Large two-chain protein |
| Relation to SNAP-25 | — | Copies residues 12–17 | Copies residues 12–19 | Cleaves between residues 197 and 198 |
| Proposed action | Forms the SNARE bundle | Competes during assembly | Competes during assembly | Removes the C-terminal nine residues |
| Reversibility | — | Competitive | Competitive | Irreversible cleavage |
From Argireline to Snap-8
The first peptide of this type in the literature is Argireline, acetyl hexapeptide-3, described by Blanes-Mira and colleagues in 2002. They identified Ac-EEMQRR-NH2 through a rational design program aimed at finding short, non-toxic sequences that interfere with SNARE assembly. In their mechanistic work, the hexapeptide inhibited neurotransmitter release in cell-based assays and interfered with the formation or stability of the SNARE complex. The same paper included cosmetic testing, which is outside the scope of this profile.
Snap-8 adds the next two residues of SNAP-25, alanine and aspartate, to the Argireline sequence. The relationship is visible in the composition: subtracting an alanine residue (C3H5NO) and an aspartate residue (C4H5NO3) from the Snap-8 formula C41H70N16O16S leaves C34H60N14O12S, the composition of the acetylated, amidated hexapeptide. The stated rationale for the longer peptide is that a closer match to the native SNAP-25 sequence should compete more effectively in the SNARE complex.
That rationale is plausible, but it should be read for what it is. Peer-reviewed, independently replicated data on the octapeptide itself are sparse. Most published descriptions of Snap-8, including comparisons with Argireline, trace back to ingredient manufacturers' technical documents rather than to journal articles with full methods. The mechanistic foundation for the whole class comes largely from the 2002 Argireline paper and from wider SNARE biology.
Snap-8 in the wider SNARE-peptide literature
Short peptides copied from SNARE motifs are a recognized research tool in their own right, and that context is more useful to a laboratory than cosmetic marketing. A 2018 study by Yang and colleagues, for example, screened peptides with the sequences of various SNARE motifs for their ability to block SNARE complex formation and mast cell degranulation. Peptides copying the N-terminal regions of VAMP2 and VAMP8 were active, and fusing a protein transduction domain to them allowed entry into cells without permeabilization.
That work illustrates two points relevant to Snap-8. First, the N-terminal ends of SNARE motifs, where zippering starts, are a sensible place to design competitive peptides. Second, a short, charged peptide does not cross a cell membrane efficiently on its own, which is why the mast cell study needed a transduction domain or permeabilization. In-vitro assays built around Snap-8, such as reconstituted SNARE assembly, liposome fusion or permeabilized-cell secretion, avoid that question, and they are the natural setting for testing whether the extra two residues change anything.
Regulatory position
Snap-8 is not an approved drug in the United States or elsewhere, and it has not been developed as one. Its regulatory identity is as a cosmetic ingredient, listed in the EU CosIng inventory as Acetyl Octapeptide-3. As a research reagent, it is supplied for in-vitro and laboratory use only.
Handling Snap-8 in the lab
- Solvent. With five charged side chains, Snap-8 dissolves readily in water. Sterile water or a neutral aqueous buffer is the usual starting point for in-vitro stocks.
- Protect the methionine. Use degassed or freshly prepared solvents where practical, avoid oxidizing additives, keep solutions cold, and do not leave stocks at room temperature longer than needed.
- Aliquot and freeze. Divide the stock into single-use aliquots to avoid repeated freeze-thaw.
- Check identity by mass. Expect a monoisotopic mass near 1074.5 Da and an average mass of 1075.2 Da. A +16 Da species indicates methionine oxidation, and a +1 Da shift can indicate deamidation. The post on how to read a certificate of analysis explains what each line on a certificate should show.
Anhydrolabs supplies Snap-8 as a lyophilized powder in vacuum-sealed vials, and also as 10-vial kits. For a copper-binding tripeptide that also has a cosmetic INCI name, see the profile of GHK-Cu.
