ARA 290 15mg

What ARA 290 is

ARA 290 is an eleven-residue linear peptide with the sequence pGlu-Glu-Gln-Leu-Glu-Arg-Ala-Leu-Asn-Ser-Ser, written pEQLERALNSS in one-letter code. Its first residue is pyroglutamic acid, in which the N-terminal amine has closed onto its own side-chain carbonyl to form a five-membered lactam, and its C-terminus is a free acid. The remaining ten residues are standard L-amino acids.

The sequence was designed from the outward-facing surface of helix B of erythropoietin, which is why the literature also describes it as a pyroglutamate helix B surface peptide. ARA 290 is a development code, and cibinetide is the International Nonproprietary Name for the same structure. Unlike most short peptides in the catalog, it has no free N-terminal amine at all, a direct consequence of that lactam ring.

ARA 290 15mg specification

How ARA 290 is analyzed

With three glutamate-derived positions, a single arginine and a blocked N-terminus, ARA 290 carries a net negative charge around neutral pH and is fairly hydrophilic; its two leucines supply most of the hydrophobic surface. It retains only modestly on C18 and comes off early in a TFA-based water/acetonitrile gradient, and a gentle ramp beginning at a small acetonitrile fraction separates it from neighbors much more cleanly than a steep generic method. No residue in the sequence is aromatic, so the 280 nm channel is essentially blank; the purity read comes from amide absorbance around 214 nm, where a clean blank run and a stable baseline matter more than usual.

Two sequence-specific impurities are worth looking for in the mass spectrum, which should otherwise center on about 1257 Da. Incomplete cyclization of the N-terminal residue leaves an open-chain variant roughly 17 to 18 Da heavier, and the Asn and Gln side chains can deamidate for a +1 Da shift that is easy to miss at low resolution. For ARA 290 15mg, the independent reverse-phase HPLC figure is published here, and a vial without any lot identifier is matched to it by crimp and cap color.

Research contexts for ARA 290

• Erythropoietin-receptor-family binding assays in cell-free or cell-culture systems
• Structural comparison of peptides derived from the helix B surface of erythropoietin
• Pyroglutamate formation and ring-opening studies by LC-MS
• Deamidation profiling of short peptides containing Asn and Gln

ARA 290 15mg is provided as an in-vitro laboratory and analytical reagent and has no application in people or animals.

ARA 290 questions

Are ARA 290 and cibinetide the same compound?

Yes. ARA 290 is the development code and cibinetide the nonproprietary name for the same pyroglutamate-capped eleven-residue sequence.

What should a mass spectrum show for ARA 290?

The free peptide should deconvolute to about 1257 Da. A signal 17 to 18 Da higher points to an uncyclized N-terminus, and a value far from 1257 suggests a different molecule or an undeclared salt or adduct.

Is ARA 290 simply a piece cut out of erythropoietin?

It is better described as a synthetic peptide designed from the surface of that protein’s helix B. The eleven-residue sequence with its pyroglutamate, not the parent protein, is what defines it.