SNAP-8 is a synthetic acetylated octapeptide, also known by the INCI-style name acetyl octapeptide-3. The SNAP-8 peptide is an eight-residue sequence modelled on the N-terminal region of SNAP-25, a protein that forms part of the SNARE complex involved in vesicle fusion. This article sets out its identity data, structure, origin and a neutral overview of how it has been studied in the laboratory.
For laboratory research use only. Not for human or veterinary use. See our research use only policy.
At a glance
- Name: SNAP-8
- Synonyms: Acetyl octapeptide-3, acetyl glutamyl heptapeptide-3
- 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
- Purity: >99% (HPLC)
- Form: Lyophilised powder
- Storage: 2-8°C, dark, upright - do not freeze. Keep sealed until use.
Structure
Sequence and terminal modifications
SNAP-8 is eight amino acids long: glutamic acid, glutamic acid, methionine, glutamine, arginine, arginine, alanine and aspartic acid. It carries two terminal modifications. The N-terminus is acetylated (Ac-) and the C-terminus is amidated (-NH2). Both modifications remove a terminal charge and are commonly used in synthetic peptides to reduce susceptibility to exopeptidases and to make the peptide more closely resemble an internal protein segment.
Charge and solubility
The sequence contains three acidic residues (two glutamic acids and one aspartic acid) and two basic arginines. With both termini capped, the overall net charge at neutral pH is slightly negative. The peptide is highly polar and water-soluble, which is typical for short sequences rich in charged residues.
The methionine residue
SNAP-8 contains a single methionine. Methionine's thioether side chain is prone to oxidation to methionine sulfoxide, which adds 16 Da to the mass. In mass spectrometry, a signal around 16 Da above the expected mass can indicate this oxidation. It is also one reason why protection from air, moisture and light is sensible when storing the material.
Origin: SNAP-25 and the SNARE complex
SNAP-25 (synaptosomal-associated protein of 25 kDa) is one of the core proteins of the SNARE complex, together with syntaxin and synaptobrevin. The SNARE complex drives the fusion of vesicles with the cell membrane, a step required for the release of neurotransmitters from nerve terminals. The structure and function of the SNARE complex have been studied extensively in cell biology.
Short peptides that mimic part of a SNARE protein sequence were investigated as potential competitors for SNARE complex assembly. The hexapeptide Ac-Glu-Glu-Met-Gln-Arg-Arg-NH2, known as acetyl hexapeptide-3 or argireline, was described by Blanes-Mira and colleagues in 2002. SNAP-8 extends this hexapeptide by two residues, alanine and aspartic acid, to give an octapeptide that corresponds to a longer stretch of the SNAP-25 N-terminal sequence.
Research overview
The published literature on SNAP-8 itself is limited compared with that on longer-established research peptides. Much of the available information on the hexapeptide parent comes from in vitro biochemical assays and cell culture work, and the octapeptide was developed as an extension of that line of research. The summary below is descriptive only.
Biochemical assays
Peptides of this family have been investigated in in vitro systems designed to measure SNARE complex formation. The rationale was that a peptide mimicking the N-terminal end of SNAP-25 might compete with the native protein for binding positions in the complex. The 2002 Blanes-Mira study reported findings for the hexapeptide in in vitro SNARE assembly assays and in cultured cells.
Cell culture models
Related work has used chromaffin cells and neuronal cultures, which are standard models for studying regulated exocytosis, to examine the effect of SNARE-mimicking peptides on secretion. Readers should note that much of the commercial literature on SNAP-8 is produced by ingredient manufacturers rather than published in independent peer-reviewed journals, and should be read with that in mind.
Comparisons with other peptides
SNAP-8 is sometimes discussed alongside GHK-Cu because both have been studied in skin-cell culture models, but the two are unrelated. GHK-Cu is a copper-binding tripeptide, while SNAP-8 is a metal-free acetylated octapeptide derived from a vesicle fusion protein. For background on the copper peptide, see our GHK-Cu copper peptide overview.
Analytical considerations
- HPLC: as a polar peptide, SNAP-8 elutes relatively early under typical reversed-phase conditions. Purity should be assessed against a single main peak.
- Mass spectrometry: the expected average mass is about 1075.2 Da. Multiply charged ions are common in ESI-MS for peptides with two arginines.
- Oxidation: a +16 Da signal points to methionine oxidation.
- Deamidation: the glutamine residue can deamidate over time, giving a +1 Da shift that is easiest to detect with high-resolution MS.
For a general walk-through of these data, see how to read a peptide certificate of analysis.
Storage
Our storage guidance for SNAP-8 is 2-8°C, dark, upright, not frozen, and kept sealed until use. Minimising exposure to air and moisture is particularly relevant because of the methionine residue. General principles are in how to store lyophilised peptides.
Regulatory note
Acetyl octapeptide-3 appears as an ingredient in some cosmetic formulations, which are regulated separately under cosmetics rules. Compound Cave SNAP-8 is not a cosmetic ingredient or a medicine. It is supplied as a laboratory research material only.
View SNAP-8 10mg in the catalogue.
Frequently asked questions
What is the sequence of SNAP-8?
SNAP-8 is Ac-Glu-Glu-Met-Gln-Arg-Arg-Ala-Asp-NH2, an N-terminally acetylated and C-terminally amidated octapeptide.
What is the CAS number of SNAP-8?
The CAS number for SNAP-8 is 868844-74-0. Its molecular formula is C41H70N16O16S and its molecular weight is 1075.2 g/mol.
How is SNAP-8 related to argireline?
Argireline (acetyl hexapeptide-3) is the six-residue sequence Ac-EEMQRR-NH2. SNAP-8 extends it by two residues, alanine and aspartic acid, to make an octapeptide.
Where does the SNAP-8 sequence come from?
It is modelled on the N-terminal region of SNAP-25, one of the core proteins of the SNARE complex involved in vesicle fusion.
Why does SNAP-8 need protection from air?
It contains a methionine residue, which can oxidise to methionine sulfoxide. Keeping the vial sealed, cool and dark reduces exposure.
References
- Blanes-Mira C, Clemente J, Jodas G, Gil A, Fernández-Ballester G, Ponsati B, Gutierrez L, Pérez-Payá E, Ferrer-Montiel A. International Journal of Cosmetic Science, 2002 (description of acetyl hexapeptide-3).
- Söllner T, Whiteheart SW, Brunner M, Erdjument-Bromage H, Geromanos S, Tempst P, Rothman JE. SNAP receptors implicated in vesicle targeting and fusion. Nature, 1993.
- PubChem compound record for acetyl octapeptide-3, National Center for Biotechnology Information.
For laboratory research use only. Not for human or veterinary use. See our research use only policy.