Vesilute

What Vesilute is, structurally

Vesilute is a dipeptide, glutamic acid joined to aspartic acid, and at 262.22 daltons the smallest compound in this catalogue by a wide margin. The deposited record for its CAS gives the same formula and name, agreeing with the product's own description.

At this size the composition can be accounted for exactly rather than inferred. Nine carbons, two nitrogens and seven oxygens across two residues leaves no ambiguity: two backbone nitrogens, one peptide bond, and three carboxyl groups, both side chains and the C-terminus.

Three acidic groups on a molecule of nine carbons makes this unusually acidic, and that governs everything below. Its isoelectric point is very low and it should be freely soluble in water. Adding acid, the reflex for a stubborn vial, is precisely the wrong move: it neutralises the carboxylates and drives the compound toward minimum solubility. Neutral water is correct, with a mildly alkaline buffer as fallback.

There is no sulfur, so no disulfide chemistry and no oxidation at sulfur, and no aromatic residue, which matters for detection below.

One degradation route a reader might expect is closed. Aspartate commonly forms a succinimide intermediate and isomerises, but that requires the backbone nitrogen of the following residue to attack the side-chain carbonyl. Here the aspartate is at the C-terminus, so there is no following residue and no nitrogen to do it. Nor is there any asparagine or glutamine, so deamidation has no site either.

Reconstitution and handling

Sterile water is the default solvent and should be entirely sufficient. A small, triply-charged, highly polar molecule dissolves readily; if a vial resists, warming and patience do more than changing solvent.

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. Acidic conditions should be avoided, since they suppress the ionisation that keeps this compound soluble.

No reducing agent is needed, since the formula contains no sulfur.

Adsorptive loss is less of a concern here than on most products in this catalogue. A small, strongly anionic molecule has little affinity for either polypropylene or glass, the latter being negatively charged itself.

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.

This is a chemically robust molecule, and the reason is worth stating: the routes that dominate peptide degradation are unavailable. There is no sulfur to oxidise, and neither deamidation nor aspartyl isomerisation has a site to act on.

What remains is hydrolysis of the single peptide bond, giving free glutamic acid and free aspartic acid. It is slow near neutral pH and accelerated at both extremes and by heat, so cold, dry, near-neutral storage addresses it. On a molecule with one peptide bond, though, a single hydrolysis destroys the compound rather than modifying it, so the consequence is more absolute than on a longer chain.

Small, highly charged solids draw moisture readily, so desiccated storage is doing real work here rather than serving as a formality.

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

How Vesilute is tested

This compound is genuinely awkward to analyse by the methods that suit the rest of this catalogue, and that is worth saying plainly.

Reversed-phase HPLC struggles on two counts. The molecule is very small and extremely polar, so it has almost nothing to bind a C18 surface with and will elute near the void volume, unseparated from salts. And it has no aromatic residue, so there is no chromophore above about 220 nm; detection relies on the single peptide bond absorbing in the low ultraviolet, a weak signal from one bond. Ion-pairing, a polar-retention stationary phase, or a non-ultraviolet detector are the usual answers.

Area percent from such a method should be treated with more caution than usual, since a compound that has not retained has not been separated from anything.

Mass spectrometry is straightforward at 262.22, and the hydrolysis products, glutamic acid at 147.13 and aspartic acid at 133.10, are well clear of the parent and of each other.

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

Handling FAQ

Should acid be used to help this dissolve? No, and it is likely to hurt. The molecule carries three carboxyl groups and its solubility depends on them being ionised. Acid suppresses that ionisation and moves the compound toward minimum solubility. Neutral water is correct.

Why is a standard HPLC purity method unsuitable? Two reasons at once. It is too polar to retain on a standard reversed-phase column and elutes near the void, and it contains no aromatic residue, so there is no strong ultraviolet chromophore. A method must address both before its purity figure means anything.

Full specifications for Vesilute.