title: Sulphonation of N-hydroxy-2-acetylaminofluorene by human dehydroepiandrosterone sulphotransferase.
abstract: 1. The aim was to determine which human recombinant sulphotransferase (ST) isoform(s) were responsible for the sulphonation and, thus, potential further bioactivation of the classical hepatic procarcinogen N-hydroxy-2-acetylaminofluorene (N-OH-2AAF). 2. N-OH-2AAF was incubated together with the cosubstrate 3'-phosphoadenosine-5'-phosphosulphate (PAPS) and either human liver cytosol or recombinant P-form phenolsulphotransferase (P-PST), M-form PST, dehydroepiandrosterone-ST (DHEA-ST) or oestrogen ST (EST). Formation of 3'-phosphoadenosine-5'-phosphate (PAP) from PAPS, measured by HPLC, was used as the assay for determination of sulphoconjugation rates. 3. The liver cytosol produced a 100% increase in PAP formation in the presence of 200 microM N-OH-2AAF as compared with baseline levels (p < 0.01), corresponding to a rate of 19 pmol/min/mg protein. Recombinant P-PST, however, was without effect. This is in contrast to previous suggestions using crude enzyme preparations. Like P-PST, recombinant M-PST and EST did not sulphonate N-OH-2AAF. On the other hand, recombinant DHEA-ST produced a 161% increase in PAP formation in the presence of 200 microM N-OH-2AAF as compared with baseline values (p < 0.001). 4. Kinetic studies of N-OH-2AAF sulphonation by DHEA-ST and human liver cytosol gave similar apparent Kms. Interestingly, the Vmax for N-OH-2AAF sulphonation by DHEA-ST was very similar to that of DHEA, the natural substrate for DHEA-ST. 5. This is the first paper to demonstrate the involvement of the human DHEA-ST in the sulphonation of an N-hydroxylated aromatic amide carcinogen.
authors.affiliation: Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston 29425, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Lewis
authors.forename: Y
authors.initials: Y
authors.lastname: Otake
authors.forename: U K
authors.initials: UK
authors.lastname: Walle
authors.forename: T
authors.initials: T
authors.lastname: Walle
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D002273:Carcinogens / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003600:Cytosol / Q000378:metabolism; D003687:Dehydroepiandrosterone / Q000737:chemistry*; D006801:Humans; D006881:Hydroxyacetylaminofluorene / Q000378:metabolism*; D007527:Isoenzymes; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry*; D015238:Sulfotransferases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000494:pharmacology; D013463:Sulfuric Acid Esters / Q000378:metabolism
chemical_list: D002273:Carcinogens; D007527:Isoenzymes; D011994:Recombinant Proteins; D013463:Sulfuric Acid Esters; D003687:Dehydroepiandrosterone; D006881:Hydroxyacetylaminofluorene; D000244:Adenosine Diphosphate; C010840:adenosine 3'-phosphate-5'-phosphate; D015238:Sulfotransferases; C019998:dehydroepiandrosterone sulfotransferase