title: HPLC/tandem ion trap mass detector methods for determination of inosine monophosphate dehydrogenase (IMPDH) and thiopurine methyltransferase (TPMT).
abstract: The efficiency of Mycophenolate mofetil (MMF) and Azathioprine (AZA) as immunosuppressive agents depends on the activity of 2 enzymes, inosine monophosphate dehydrogenase (IMPDH) and thiopurine methyltransferase (TPMT) respectively. We present preliminary evaluation of nonradioactive methods that apply HPLC with ion-trap mass detection to measure the activities of IMPDH in peripheral blood mononuclear cells (PBMC) and TPMT in the erythrocytes (RBC). We found IMPDH activity of 0.9 +/- 0.2 nmol/hour/10(6) PBMC and TPMT activity of 19.9 +/- 4.7 nmol/hour/ml RBC in healthy subjects. These methods, following its further validation, could be useful for monitoring the activity in a clinical and experimental setting.
authors.affiliation: Heart Science Centre, Imperial College, London, UK.
authors.forename: K
authors.initials: K
authors.lastname: Kalsi
authors.forename: A M
authors.initials: AM
authors.lastname: Marinaki
authors.forename: M H
authors.initials: MH
authors.lastname: Yacoub
authors.forename: R T
authors.initials: RT
authors.lastname: Smolenski
mesh_terms: D001379:Azathioprine / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007168:IMP Dehydrogenase / Q000032:analysis* / Q000096:biosynthesis / Q000737:chemistry*; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007477:Ions; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods*; D008780:Methyltransferases / Q000032:analysis* / Q000096:biosynthesis / Q000737:chemistry*; D009173:Mycophenolic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D012107:Research Design
chemical_list: D007166:Immunosuppressive Agents; D007477:Ions; D007168:IMP Dehydrogenase; D008780:Methyltransferases; C022745:thiopurine methyltransferase; D009173:Mycophenolic Acid; D001379:Azathioprine