HUMAN LIVER STEROID SULFOTRANSFERASE SULFATES BILE-ACIDS


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RADOMINSKA A., COMER K., ZIMNIAK P., FALANY J., ISCAN M. , FALANY C.

BIOCHEMICAL JOURNAL, vol.272, no.3, pp.597-604, 1990 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 272 Issue: 3
  • Publication Date: 1990
  • Doi Number: 10.1042/bj2720597
  • Title of Journal : BIOCHEMICAL JOURNAL
  • Page Numbers: pp.597-604

Abstract

The sulphation of bile acids is an important pathway for the detoxification and elimination of bile acids during cholestatic liver disease. A dehydroepiandrosterone (DHEA) sulphotransferase has been purified from male and female human liver cytosol using DEAE-Sepharose CL-6B and adenosine 3', 5'-diphosphate-agarose affinity chromatography [Falany, Vazquez & Kalb (1989) Biochem. J. 260, 641-646]. Results in the present paper show that the DHEA sulphotransferase, purified to homogeneity, is also reactive towards bile acids, including lithocholic acid and 6-hydroxylated bile acids, as well as 3-hydroxylated short-chain bile acids. The highest activity towards bile acids was observed with lithocholic acid (54.3 +/- 3.6 nmol/min per mg of protein); of the substrates tested, the lowest activity was detected with hyodeoxycholic acid (4.2 +/- 0.01 nmol/min per mg of protein). The apparent K(m) values for the enzyme are 1.5 +/- 0.31-mu-m for lithocholic acid and 4.2 +/- 0.73-mu-m for taurolithocholic acid. Lithocholic acid also competitively inhibits DHEA sulphation by the purified sulphotransferase (Ki 1.4-mu-m). No evidence was found for the formation of bile acid sulphates by sulphotransferases different from the DHEA sulphotransferase during purification work. The above results suggest that a single steroid sulphotransferase with broad specificity encompassing neutral steroids and bile acids exists in human liver.