Abstract
Objectives: To compare 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG) as substrates for the methylation reaction catalysed by the enzyme thiopurine S-methyltransferase (TPMT).
Methods: TPMT activity in haemolysed red blood cells of healthy blood donors was determined twice, using the same experimental setting and equal molar concentrations of 6-TG and 6-MP as substrates. After extraction, the reaction products 6-methyl-TG and 6-methyl-MP were quantified using specific high-performance liquid chromatography procedures.
Results: The medians of the TPMT activities from 199 blood donors were 54.4 nmol 6-MTG g−1Hb h−1 when measured with 6-TG as the substrate and 35.8 nmol 6-MMP g−1 Hb h−1 when measured with 6-MP. The correlation coefficient for the 199 pairs of values was 0.8695. On average, TPMT activity was 34% lower with 6-MP as substrate than with 6-TG as substrate.
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Received: 4 October 1999 / Accepted in revised form: 15 March 2000
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Kröplin, T., Iven, H. Methylation of 6-mercaptopurine and 6-thioguanine by thiopurine S-methyltransferase A comparison of activity in red blood cell samples of 199 blood donors. E J Clin Pharmacol 56, 343–345 (2000). https://doi.org/10.1007/s002280000137
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DOI: https://doi.org/10.1007/s002280000137