ARA-290 is a development code, not a chemical name. This page sets out the identity of ARA-290: what the sequence is, what mass to expect, how it behaves under reverse-phase HPLC, and how a buyer can confirm that the material in a vial is what the label says. It is silent on what ARA-290 does, and preparation, handling and dosing are not covered.
The sequence behind ARA-290
ARA-290 is an 11-residue linear peptide with the sequence pGlu-Glu-Gln-Leu-Glu-Arg-Ala-Leu-Asn-Ser-Ser, often written in one-letter code as pEQLERALNSS. The first residue is pyroglutamic acid (pGlu), a cyclised form in which the N-terminal amine has closed onto its own side-chain carbonyl to form a five-membered lactam ring. The remaining ten residues are standard L-amino acids, and the C-terminus is a free acid.
The molecular formula is C51H84N16O21 and the average molecular mass is approximately 1257.3 g/mol. As with any short peptide, that number is the first sanity check against a mass-spectrometry trace: an observed mass that does not sit at or near 1257 for the free peptide means either the material is something else or a salt or adduct has not been accounted for.
What the name ARA-290 refers to
The sequence was designed from a surface of erythropoietin: it corresponds to residues that face outward from helix B of that protein, which is why the compound is also described in the literature as a pyroglutamate helix B surface peptide. The designation ARA-290 is a developmental code, and cibinetide is its International Nonproprietary Name. Both names point to the same eleven-residue structure.
The practical consequence is the same as for every coded compound in this series. Neither name constrains what is actually in a vial; only the sequence does. A certificate that says “ARA-290” without printing pEQLERALNSS, or that prints a sequence starting with a plain glutamine or glutamic acid, is describing something that may not be the same molecule.
How a polar, acidic 11-mer behaves on reverse-phase HPLC
Looking at the composition explains the chromatography. Three of the eleven positions are glutamic acid or its cyclised form, there is one arginine, and the rest are dominated by small or polar residues (serine, asparagine, glutamine, alanine) with two leucines providing most of the hydrophobic surface. Because the N-terminal pGlu has no free amine, the peptide carries no positive charge at that end, and the overall net charge around neutral pH is negative.
The result is a fairly hydrophilic peptide that retains only modestly on a C18 column and elutes in the early part of a typical water/acetonitrile gradient with trifluoroacetic acid as the ion-pairing agent. A shallow gradient with a low starting organic percentage separates it from nearby impurities much better than a steep generic method.
Detection wavelength matters here. ARA-290 contains no tryptophan, tyrosine or phenylalanine, so it has essentially no useful absorbance at 280 nm. It has to be read on the peptide bond at around 214 nm, where mobile-phase components also absorb, so a clean blank run and a stable baseline are part of a credible chromatogram.
What an analysis for ARA-290 should show
A useful certificate reports the column chemistry and dimensions, mobile phases and gradient, detection wavelength, retention time, the integrated peak with its integration window visible, and a mass confirmation. Our guide on how to read an HPLC chromatogram covers each of those elements in turn.
Two sequence-specific points are worth checking. The first is the N-terminus. Pyroglutamate is formed from an N-terminal glutamine or glutamic acid, and incomplete cyclisation leaves an open-chain variant that differs in mass by roughly 17 to 18 Da depending on the precursor residue. That species usually elutes close to the main peak, so a mass spectrum is more informative than retention time alone. The second is deamidation: asparagine and glutamine can convert to their acidic forms, giving a +1 Da shift that is easy to miss at low resolution. Both are covered in more detail in our article on peptide synthesis impurities.
Expect the ARA-290 report to give net peptide content as a separate number from HPLC purity, and to name the counter-ion. With only one basic residue and no free N-terminal amine, ARA-290 binds less trifluoroacetate than a strongly basic peptide of similar size, but the counter-ion still adds mass, and purity by HPLC is not the same number as the amount of peptide in the vial. See peptide purity vs net peptide content for why the two figures differ.
Confirming identity independently
Look ARA-290 up by its sequence rather than by its trade name. Public chemical and protein databases index this compound under its structure and under the cibinetide name, and a search on pEQLERALNSS (remembering the pyroglutamate at position one) will show quickly whether the formula and mass a vendor is quoting match the pairing used everywhere else. Direct identity links for ARA-290 sit on the product page.
How ARA-290 is supplied here
ARA-290 15mg is supplied as a lyophilised powder in a sealed vial. ARA-290 carries its own published reverse-phase HPLC result from an independent laboratory. You will find the ARA-290 vial size and its published HPLC purity on the product page. ARA-290 vials are not lot-numbered, and it is matched to its published HPLC result by crimp and cap color.
Frequently asked questions
What is the amino acid sequence of ARA-290?
pGlu-Glu-Gln-Leu-Glu-Arg-Ala-Leu-Asn-Ser-Ser (pEQLERALNSS), eleven residues with an N-terminal pyroglutamate and a free C-terminal acid.
Are ARA-290 and cibinetide the same compound?
Yes. ARA-290 is the developmental code and cibinetide is the International Nonproprietary Name for the same eleven-residue sequence.
What molecular weight should I expect for ARA-290?
Approximately 1257.3 g/mol for the free peptide, formula C51H84N16O21. Any counter-ion adds to the weighed mass of ARA-290, so it should be declared with the figure.
Why is ARA-290 read at 214 nm rather than 280 nm?
Because it has no aromatic residues. Without tryptophan, tyrosine or phenylalanine there is nothing to absorb meaningfully at 280 nm, so detection relies on the peptide bond at around 214 nm.
Research use only. All products supplied by Battle Born Peptides are laboratory reference materials for in-vitro research and analytical use by qualified professionals. They are not drugs, foods, dietary supplements, cosmetics or medical devices; they are not approved by the FDA or any other regulator for use in humans or animals; and they are not intended to diagnose, treat, cure, mitigate or prevent any disease, or to affect the structure or any function of the body of humans or animals. Nothing in this article is preparation, handling or dosing guidance. See our full research-use terms.