title: Isoelectric profiles of human erythropoietin are different in serum and urine.
abstract: By adding a step of immunoaffinity to the method we had previously developed for analysing erythropoietin (EPO) in urine, we were able to study the isoelectric profiles of this hormone in human serum samples. This method was sensitive enough to investigate samples presenting physiological levels of this hormone. Comparison with the corresponding profiles in urine showed that natural EPO was systematically more acidic in urine. The acidification process, which was not patent in the non-human primate Cynomolgus macaque, clearly also affected recombinant EPO when injected into humans. This process was unrelated to any enzymatic activity in urine since the incubation of natural or recombinant EPO in urine induced no transformation of their isoelectric profiles. The nature and mechanism of the structural modifications occurring during the renal handling of this hormone remain to be investigated.
authors.affiliation: Agence Française de Lutte contre le Dopage, Département des Analyses, 143 Avenue Roger Salengro, 92290 Châtenay-Malabry, France. f.lasne@afld.fr
authors.forename: Françoise
authors.initials: F
authors.lastname: Lasne
authors.forename: Laurent
authors.initials: L
authors.lastname: Martin
authors.forename: Jean Antoine
authors.initials: JA
authors.lastname: Martin
authors.forename: Jacques
authors.initials: J
authors.lastname: de Ceaurriz
mesh_terms: D000818:Animals; D004921:Erythropoietin / Q000097:blood* / Q000652:urine*; D006801:Humans; D007525:Isoelectric Focusing; D007526:Isoelectric Point; D008252:Macaca fascicularis; D011994:Recombinant Proteins; D013045:Species Specificity
chemical_list: D011994:Recombinant Proteins; D004921:Erythropoietin