PHOSPHOROTHIOATE OLIGONUCLEOTIDE METABOLISM: CHARACTERIZATION OF THE “N+”-MER BY CE AND HPLC-ES/MS

Unique phosphorothioate oligonucleotide metabolites of ISIS 2302 were isolated from pig kidney and characterized by capillary electrophoresis (CE) and high pressure liquid chromatography-electrospray mass spectrometry (HPLC-ES/MS) analysis. Fractionation by anion exchange HPLC followed by CE and HPLC-ES/MS analysis enabled facile identification of many metabolites, including a unique metabolite that has a slower migration time than intact ISIS 2302. The appearance of this slower migrating “N+” metabolite in CE analysis was correlated to three masses observed during HPLC-ES/MS analysis. These masses are consistent with the addition of a ribonucleotide or a phosphorothioate deoxyribonucleotide to intact ISIS 2302. © 1997 Elsevier Science Ltd.