Abstract
Background and objectives: Previous studies have demonstrated the metabolism of tibolone through sulfation, with the cytosolic sulfotransferase (SULT) SULT2A1 as the major responsible enzyme. The current study aimed to investigate how SULT2A1 genetic polymorphisms may affect the dehydroepiandrosterone (DHEA)- and tibolone-sulfating activity of SULT2A1. Methods: Site-directed mutagenesis was employed to generate cDNAs encoding ten different SULT2A1 allozymes. Recombinant SULT2A1 allozymes were expressed in BL21 E. coli cells, and purified using glutathione-sepharose affinity chromatography. An established sulfotransferase assay was used to analyze DHEA- and tibolone-sulfating activity of the purified SULT2A1 allozymes. Results: The nine human SULT2A1 allozymes plus the wild-type SULT2A1 were found to display differential sulfating activity toward DHEA and tibolone. Kinetic analysis revealed that different SULT2A1 allozymes exhibited differential substrate affinity and catalytic efficiency toward the two substrates tested. Conclusion: The results obtained provided useful information concerning the differential metabolism of tibolone through sulfation in individuals with different SULT2A1 genotypes.