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Molecular Weight
Purity
Storage
Appearance
Solubility
01
ARA-290, also known by its international non-proprietary name cibinetide, is an 11-residue linear peptide designed from the helix-B surface of human erythropoietin (EPO). Its sequence, pGlu-Glu-Gln-Leu-Glu-Arg-Ala-Leu-Asn-Ser-Ser, begins with a pyroglutamate residue that caps the N-terminus.
EPO acts through two different receptor assemblies: a homodimer of the EPO receptor, which drives red blood cell production, and a heterodimer of the EPO receptor with the β-common receptor (CD131), often called the innate repair receptor (IRR), which is linked to tissue-protective and anti-inflammatory signalling. ARA-290 was designed to engage the second without activating the first. It is supplied as a lyophilized reference material for in vitro research on this receptor system and for analytical work on pyroglutamate-capped peptides.
02
ARA-290 is a short, hydrophilic peptide with a capped N-terminus.
Origin in EPO helix B
The sequence mirrors part of the exposed surface of EPO’s helix B, the region associated with the tissue-protective receptor complex rather than the erythropoietic homodimer.
Pyroglutamate cap
The N-terminal residue is pyroglutamic acid, a cyclised form of glutamine or glutamate. It removes the free N-terminal amine, protects against aminopeptidases and blocks Edman sequencing.
Hydrophilic composition
Three glutamates, a glutamine, an asparagine, two serines and an arginine make it very water-soluble, with only two leucines and an alanine as hydrophobic residues.
Asn9-Ser10
An asparagine followed by serine is one of the faster-deamidating sequence motifs, making this the peptide’s main chemical weak point.
No sulfur or aromatic residues
There is no cysteine, methionine, tryptophan, tyrosine or histidine, so disulfide and oxidation issues are minimal, and UV detection relies on the peptide bonds.
03
Research on ARA-290 focuses on the innate repair receptor and on separating the tissue-protective and blood-forming effects of EPO.
Receptor selectivity
ARA-290 was designed to interact with the EPO receptor/β-common receptor complex while not activating the EPO receptor homodimer responsible for red blood cell production.
Cell-based studies
In vitro work in macrophage, microglial, endothelial and other cell systems has examined effects on inflammatory cytokine release and on cell survival under stress.
Published research context
The compound has been studied in preclinical models and in clinical research. These studies are cited only as background to its receptor pharmacology; no outcomes are claimed for this material.
Characterisation of the reference material itself is limited to in vitro and analytical work.
04
Innate repair receptor studies
A reference ligand for probing EPO receptor/β-common receptor signalling in cultured cells.
Separating EPO pathways
Used alongside EPO to distinguish tissue-protective signalling from erythropoietic signalling, including in receptor knockdown or knockout systems.
Anti-inflammatory assays
Used in cytokine-release assays in macrophage and microglial cultures.
pGlu-peptide analytics
A model compound for identity methods for N-terminally blocked peptides, where Edman sequencing cannot be used directly.
05
Storage
Store the lyophilized powder at −20 °C, sealed, desiccated and protected from light. Let the vial reach room temperature before opening.
Reconstitution
Dissolves readily in water or aqueous buffer across the usual pH range.
Deamidation
Asn9, which is followed by serine, can deamidate to aspartate and isoaspartate, particularly at neutral to basic pH and higher temperatures. Use solutions promptly, keep them cold, and freeze single-use aliquots for longer storage.
Other pathways
With no cysteine or methionine, disulfide scrambling and oxidation are not significant concerns. Gln3 can also deamidate more slowly.
Labware
Use low-binding polypropylene tubes and avoid repeated freeze–thaw cycles. Water and counter-ion content for each lot are given on the certificate of analysis.
06
ARA-290 is straightforward to separate but requires care for identity and deamidation.
HPLC
Reversed-phase C18 with a 0.1% TFA water/acetonitrile gradient gives a single sharp peak with relatively early retention because of its hydrophilic composition. Detect at about 214 nm.
Mass spectrometry
ESI-MS shows [M+H]⁺ at m/z 1257.6 and [M+2H]²⁺ at m/z 629.3, consistent with the monoisotopic mass of 1256.60 Da.
Sequencing
The pyroglutamate blocks Edman degradation from the first cycle. MS/MS of the intact peptide is the preferred identity method; alternatively, pyroglutamate aminopeptidase can remove the cap before Edman sequencing.
Impurity profile
Typical checks include Asn9 deamidation products (+1 Da, including isoaspartate forms), the uncyclised Gln1 or Glu1 precursor, truncated sequences and counter-ion content.
07
Yes. Cibinetide is the international non-proprietary name for ARA-290. Both refer to pGlu-Glu-Gln-Leu-Glu-Arg-Ala-Leu-Asn-Ser-Ser, CAS 1208243-50-8.
It was designed not to. ARA-290 targets the EPO receptor/β-common receptor complex linked to tissue protection and was engineered to avoid activating the EPO receptor homodimer that drives red blood cell production. Published research describes it as non-erythropoietic.
pGlu-Glu-Gln-Leu-Glu-Arg-Ala-Leu-Asn-Ser-Ser with a free C-terminal acid: 11 residues, C₅₁H₈₄N₁₆O₂₁, 1257.3 g/mol.
Store the lyophilized powder at −20 °C, sealed, desiccated and protected from light. After reconstitution, keep solutions cold and use them promptly, or freeze single-use aliquots, mainly to limit deamidation at Asn9.
Edman chemistry needs a free N-terminal amine, and the N-terminal pyroglutamate is a cyclic residue without one. MS/MS is used instead, or the cap is first removed with pyroglutamate aminopeptidase.
Deamidation of Asn9, which sits next to serine, forming aspartate and isoaspartate variants. Oxidation and disulfide chemistry are minor concerns because there is no methionine or cysteine.
No. It is supplied strictly as a reference compound for laboratory and analytical research and is not for human or animal use.
ARA-290 Research Reference. (2026). Pure Peptides Labs Research Catalogue. Retrieved from https://purepeptideslabs.net/research-catalogue/structural-research-peptides/ara-290/
Materials listed on this platform are supported by independent testing and published documentation for laboratory research contexts.
