Endocrine steroid sulfotransferases: steroid alcohol sulfotransferase from human breast carcinoma cell line MCF-7.
Steroid alcohol sulfotransferase (SAS) has been isolated from the cytosol of a human breast carcinoma cell line, MCF-7. This enzyme from Sephadex G-200 chromatography displayed a mol. wt of 118 KDa. The conditions for optimal enzymic activity of SAS were determined to be 20 min incubations at 45 degrees C in 0.2 M Tris buffer (pH 7.5) containing 0.06 M Mg2+. Chromatofocusing chromatography also yielded a single peak of SAS with a pI of 5.8. Results from the incubations of a series of androstane analogues revealed that SAS required a 3 beta-hydroxyl on a steroid with the trans bridge between the A and B rings. Neither the 3 beta-allylic hydroxyl group nor the A-ring phenolic 3-hydroxyl accepted the sulfate group from 3'-phosphoadenosine-5'-phosphosulfate. D-ring beta-hydroxyl groups were tolerated by the enzyme, however, alpha-hydroxyl groups on the D-ring appeared to interfere with the reaction. Sulfurylation of steroids by SAS was related inversely to the sum of the displacements of the 3-hydroxyl plus that of the 17-hydroxyl groups relative to the plane of symmetry of the dehydroepiandrosterone nucleus. This enzyme was also capable of sulfurylating short chain aliphatic alcohols, although at greatly reduced rates. 3 beta-Chloro-5-androstene-17-one and 2-nitroestradiol. 17 beta proved to be the best inhibitors of SAS.
D001943:Breast Neoplasms / Q000201:enzymology*; D002460:Cell Line; D055598:Chemical Phenomena; D002621:Chemistry; D003600:Cytosol / Q000201:enzymology; D003687:Dehydroepiandrosterone / Q000031:analogs & derivatives / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013431:Sulfates / Q000378:metabolism; D015238:Sulfotransferases; D013466:Sulfurtransferases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*
D013431:Sulfates; D003687:Dehydroepiandrosterone; D013466:Sulfurtransferases; D015238:Sulfotransferases; C028152:alcohol sulfotransferase