ARA-290

1 Identity

Synthetic linear 11-residue peptide with a pyroglutamate N-terminus; erythropoietin helix-B surface sequence

Sequence

PyroGlu-Glu-Gln-Leu-Glu-Arg-Ala-Leu-Asn-Ser-Ser-OH — pGlu-EQLERALNSS. Eleven residues, all L. The N-terminal glutamine is present as pyroglutamate (5-oxo-L-proline), so the alpha-amino group is cyclized and blocked; free C-terminal acid on Ser11. No disulfide, no cysteine, no acylation, no amidation, and no aromatic residue anywhere in the chain — therefore no 280 nm chromophore, which is a method constraint and not a footnote. The sequence reproduces a solvent-exposed segment of helix B of human erythropoietin and reproduces none of the erythropoietin receptor-binding face; it is not an erythropoietin analog in any structural sense. Supplied as the acetate salt — one reagent catalog writes C51H84N16O21 . XC2H4O2 — or as the trifluoroacetate.

Molecular formula

C51H84N16O21 (free base)

Average mass

1257.324 Da (C51H84N16O21).

Monoisotopic mass

1256.59969 Da. [M+H]+ m/z 1257.6070; [M+2H]2+ m/z 629.3071.

Salt / variant note

A single molecule commercially — no rival construct is sold under the name ARA-290 or cibinetide — so the risk here is not substitution but incomplete cyclization, and the near-isobaric set is unusually tight. (1) Uncyclized open-chain Gln1 material, C51H87N17O21, 1274.36 average / 1273.6262 monoisotopic, plus 17.03 Da: the direct synthesis-related failure, and the reason the pyroglutamate is a release attribute rather than a naming convention. (2) The N-terminal glutamine deamidation product, open-chain Glu1, C51H86N16O22, 1275.34 / 1274.6103, plus 18.02 Da. (3) The C-terminal amide, C51H85N17O20, 1256.34 / 1255.6157, minus 0.98 Da from the target — a one-dalton substitution invisible to any whole-dalton tolerance. (4) Asn9 deamidation to Asp9, C51H83N15O22, 1258.31 / 1257.5837, plus 0.98 Da — the second predictable degradation route in this sequence and the exact mirror image of the amide error, so a mass one dalton off in either direction has two different explanations and a certificate must say which. The isoAsp9 form is exactly isobaric with the Asp9 form, so mass cannot separate the two and the release certificate must name a chromatographic method that does. (5) Salt form is the other axis: free base against acetate against trifluoroacetate, with Arg6 the single basic center against three carboxylates plus a blocked N-terminus, so counterion loading is low but not zero and is measured rather than assumed.

2 Class & testing panel

Form

Single article

Testing panel

P3 — panel definition

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

In-vitro receptor and cell work, a substantial rodent literature, and a small number of sponsor- and investigator-run randomized placebo-controlled Phase 2 studies, each enrolling in the tens of participants, with registered trial identifiers and peer-reviewed publications. There is no Phase 3 program, no marketing authorization in any jurisdiction and no large independent replication; the compound remains investigational. Specific trial identifiers and PMIDs are on the citation index page.

4 Storage & specification

Storage

Lyophilized powder in a Type I amber glass vial, -20 degrees C plus or minus 5 degrees C, desiccated with in-pack desiccant, protected from light, stoppered and crimped. Reconstituted solution is not a company presentation; the vial ships and is stored dry. Equilibrate the sealed vial to room temperature before opening. Ships ambient with a labeled cumulative excursion allowance recorded on the shipping record; a single-use temperature logger travels in every export carton.

Shelf life

Provisional 24 months at -20 degrees C plus or minus 5 degrees C from the date of QA release, pending the company's own long-term and accelerated stability data on the first three lots, with the N-terminal pyroGlu against open-chain Gln1 pair as the stability-indicating attribute to trend, alongside the Asn9 deamidation product and total related substances.