EPO (Erythropoietin / Epoetin alfa)

1 Identity

Recombinant human glycoprotein hormone, CHO-expressed, 165 amino acids in the marketed product, of which approximately 40 percent of the mass is carbohydrate. Three N-glycosylation sites and one O-glycosylation site; two disulfides. Not A peptide, and not specifiable as one.

Sequence

Recombinant glycoprotein, sequence not reproduced. 165 residues in the marketed product; the UniProt P01588 mature chain is 166 residues, with Arg166 removed post-translationally. Disulfides at mature Cys7-Cys161 and Cys29-Cys33.

Molecular formula

C815H1317N233O241S5 describes the polypeptide backbone only. The glycosylated drug substance has no single molecular formula: glycan occupancy and sialylation vary lot to lot by design. Any certificate quoting a discrete formula for this article is describing a molecule that does not exist in the vial. One seller's own product page prints this backbone formula together with a mass of 18396.1, which is the deglycosylated protein and cannot be what is in the vial it offers.

Average mass

30,400 Da for the drug product per the FDA Epogen label. Deglycosylated backbone 18,396.19 Da. Both figures belong on a record for this article, and the distinction between them is the whole point.

Monoisotopic mass

Not available, and not definable for a heterogeneously glycosylated 30 kDa glycoprotein.

Salt / variant note

Darbepoetin alfa, hyperglycosylated with five N-glycans at approximately 37 kDa, a distinct INN and CAS. Methoxy polyethylene glycol-epoetin beta at approximately 60 kDa. Epoetin beta, theta, zeta, omega and kappa are different glycoforms of the same 165-residue backbone, which means peptide mapping alone cannot distinguish them and only isoform distribution can. EPO-Fc fusions. Peginetide, a wholly synthetic dimeric peptide EPO-receptor agonist withdrawn in 2013, which gray-market lists sometimes file under "EPO". And invented listings such as "EPO-5", of no determinable composition.

2 Class & testing panel

Form

Single article

Testing panel

Special-class panel — panel definition

3 Primary sources & evidence

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

Regulatory evidence is complete and authoritative: BLA 103234 approved 1 June 1989, and the first biosimilar, Retacrit, approved May 2018 under section 351(k). Analytical evidence is the point of the record: this article cannot be characterized by the methods this catalog uses for peptides, and saying so is the finding.

4 Storage & specification

Storage

Not assigned. The article is not offered.

Shelf life

Not assigned. The article is not offered.