Snap-8

What Snap-8 is, structurally

Snap-8 is an octapeptide with both ends blocked: acetylated at the N-terminus and amidated at the C-terminus. The product page gives the sequence in describing how the compound relates to the shorter acetyl hexapeptide-3, the same first six residues without the terminal alanine and aspartate.

That sequence reconciles with the supplied formula completely, which is worth stating because it makes this one of the better-specified products in the catalogue. Building the formula from the residues gives C41H70N16O16S and an average mass of 1075.17, against a stated 1075.17. The nitrogen and oxygen counts check independently as well: sixteen nitrogens are eight backbone amides, one C-terminal amide and seven on side chains, which is exactly what two arginines at three each and one glutamine supply. Sixteen oxygens are eight backbone carbonyls, one from the acetyl group and seven on side chains, which two glutamates, one aspartate and one glutamine supply exactly.

Both blocked termini have practical consequences. The acetyl group removes the free alpha-amino group, so Edman degradation cannot sequence this peptide and confirmation must come from mass spectrometry. The C-terminal amide removes the negative charge a free carboxyl would carry, though with two glutamates and an aspartate present the molecule retains substantial acidic character alongside its two arginines. The result is a peptide carrying both strongly acidic and strongly basic side chains, which keeps it charged across a wide pH range and should make it freely water soluble.

The single sulfur is the methionine at position three. That gives one oxidation route, to the sulfoxide, adding sixteen units. There is no cysteine, so no disulfide and no thiol chemistry.

Reconstitution and handling

Sterile water is the default solvent and should be sufficient. A peptide carrying charges of both signs remains soluble across a wide pH range and rarely needs help dissolving.

Add diluent slowly down the inside wall of the vial, swirl gently, and let the solution clarify. Do not vortex; it introduces foam without dissolving anything faster.

Ordinary neutral buffers are suitable, and the mixed charge makes this molecule less sensitive to buffer pH than one dominated by acidic or basic residues alone.

No reducing agent is needed, since the single sulfur is a methionine thioether and there is no disulfide to protect.

Adsorptive loss deserves the usual allowance at low concentration, with low-protein-binding tubes reducing it.

This is laboratory preparation chemistry, not dosing, administration, or protocol guidance of any kind.

Storage and stability

Store the lyophilized powder at -20 degrees C, sealed, desiccated and protected from light, and let a cold vial warm before opening. Reconstituted, hold at 2 to 8 degrees C, or aliquot and freeze rather than thawing repeatedly.

Methionine oxidation is the principal named liability, adding sixteen units as the sulfoxide, and air, warmth and light all accelerate it. A sealed, cold, dark vial is the control.

The glutamine is the deamidation candidate, converting to glutamate and adding about one unit, and the two aspartate and glutamate positions carry the ordinary isomerisation liability. Both reactions need water, so the dry solid is largely protected while solutions are not, and warmth and alkaline pH accelerate them.

The C-terminal amide is a third route. Hydrolysis converts it to the free acid, adding about one unit and restoring a negative charge, which is a change of substance rather than simple degradation. Near-neutral storage limits it.

Because deamidation and amide hydrolysis both add approximately one unit, a single mass reading will not distinguish them, and chromatographic behaviour is what separates the two.

These are storage conditions for the material, not dosing or administration guidance.

How Snap-8 is tested

Reversed-phase HPLC establishes chromatographic purity as area percent. A peptide carrying charges of both signs retains moderately on a standard C18 column, and trifluoroacetic acid in the mobile phase helps both retention and peak shape.

Detection should be assumed near 214 nm. The sequence contains no tryptophan, tyrosine or phenylalanine, so 280 nm detection is not available here, and that is a definite conclusion rather than an assumption because the sequence is known.

Area percent is a chromatographic measure and not peptide content by weight. Solid-phase synthesis delivers a salt, and residual trifluoroacetate is its own impurity class.

Mass spectrometry confirms identity against 1075.17. A result sixteen units high indicates the methionine sulfoxide. A result about one unit high indicates either deamidation of the glutamine or hydrolysis of the C-terminal amide, which mass alone cannot separate.

These describe general methodology, not a claim about any particular batch.

Handling FAQ

Can this peptide be sequenced by Edman degradation? No. The N-terminus is acetylated, and Edman chemistry requires a free alpha-amino group to attack. Sequence confirmation has to come from mass spectrometry instead.

Is 280 nm detection available? No. The sequence contains no aromatic residues, so there is nothing to absorb at that wavelength, and detection should be at 214 nm where the peptide bond absorbs.

Full specifications for Snap-8.