What is ARA-290?
The molecular reference for this catalog records the sequence H-Pyr-Glu-Gln-Leu-Glu-Arg-Ala-Leu-Asn-Ser-Ser-OH across 11 residues. The amino terminus is pyroglutamate, a cyclised glutamate that blocks aminopeptidase attack and removes the free alpha amino group, which also changes how the peptide behaves in amine reactive labelling chemistry. The chain is acidic, carrying two glutamates against a single arginine.
The design logic in the published literature is separation of function. Erythropoietin signals through two receptor populations, the classical homodimeric receptor associated with red cell production and a heteromeric complex with the beta common receptor subunit, sometimes called the innate repair receptor. ARA-290 reproduces only the helix B face that contacts the second complex, so cell and rodent models use it to engage that pathway without the erythropoietic arm (Brines, 2008).
What is not settled includes the composition of that receptor complex in several tissues, the short plasma residence of an unmodified 11-residue chain relative to the duration of effects reported in rodent models, and whether results across neuropathy and inflammation models share one upstream mechanism.
Reconstitution & handling
Sterile or bacteriostatic water dissolves this peptide readily, and it is added slowly down the vial wall with gentle swirling rather than shaking. Because the sequence is acidic, solubility is good at neutral pH and improves slightly in mildly basic buffer, while strongly acidic diluents reduce it. Concentration is a straightforward division, so 1 mL added to a 5 mg vial gives 5 mg per millilitre.
Storage & stability
Sealed lyophilized vials are kept at -20 °C away from light and moisture and brought to room temperature before opening so condensation does not reach the powder. Reconstituted solution is refrigerated at 2 to 8 °C and split into single use aliquots, and repeated freezing and thawing is avoided. The asparagine residue makes prolonged warm storage in solution inadvisable, as deamidation is a known route to charge variants.
How it's tested
Lots are characterised by reversed phase HPLC at 214 and 220 nm and reported at 99 percent or greater main peak area, a pair chosen because the sequence has no tryptophan or tyrosine and absorbs weakly at 280 nm. Mass spectrometry confirms identity against the theoretical average mass of 1257.3 from C55H89N17O21, which also resolves the pyroglutamate form from an uncyclised variant. A lot-matched certificate is available on request.