losartan-potassium and caffeic-acid

Mass spectrometric analyses of the recombinant proteins in Eprex and Aranesp were undertaken with the goal of producing reference mass spectra and evaluating strategies to improve its applicability as a method for equine and canine doping control of these substances. A simple, low chemical noise deglycosylation reaction removed microheterogeneity due to post-translational carbohydrate attachment and both proteins were detectable using MALDI-TOF-MS. Deglycosylated human erythropoietin (hEPO) was also detected using HPLC-ESI-MS. This is the first time that spectra of deglycosylated Eprex and Aranesp have been published. Eight synthetic reference standards, which match peptides produced by endoproteinase Glu-C enzymatic cleavage of Aranesp and/or Eprex, were analysed by ESI-MS and ESI-MS-MS. The E12 Glu-C peptide, common to both proteins, was detected at the low femtomole-level using gradient nano-HPLC-ESI-MS-MS in the positive ion mode.

Topics: Caffeic Acids; Carbohydrates; Chromatography, High Pressure Liquid; Darbepoetin alfa; Disulfides; Doping in Sports; Erythropoietin; Glycosylation; Humans; Hydrolysis; Indicators and Reagents; Nanotechnology; Recombinant Proteins; Reference Standards; Spectrometry, Mass, Electrospray Ionization; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization