Aryl sulfotransferase

Aryl sulfotransferases catalyze the transfer of the sulfuryl moiety from 3 -phosphoadenosine 5 -phosphosulfate to phenols, catechols, benzylic alcohols, arylhydroxylamines, and arylhydroxamic acids. This assay measures adenosine 3, 5 -diphosphate and is thus suited to quantitate enzyme activity when the sulfate esters formed are chemically unstable. 

Separation of 3 -phosphoadenosine 5 -phosphosulfate and adenosine 3, 5 -diphosphate is carried out on an Econosphere Ci8 column (4.6 mm x 250 mm, 5 fim) at ambient temperature. The mobile phase was water-methanol (88 12) containing 75 mM KH2P04, 1 mM 1-octylamine, and 100 mM ammonium chloride. The pH was adjusted to 5.45 with KOH before the addition of methanol. Detection was by measuring absorbance at 254 nm. 

Assay mixtures contained 200 fiM 3 -phosphoadenosine 5 -phosphosulfate, 0.25 M phosphate buffer (pH 7.0), 8.3 mM 2-mercaptoethanol, acceptor substrate (e.g., 1-naphthalenemethanol) in acetone ( 5% (v/v) final concentration in assay), and 0.5 to 3.0 fig of aryl sulfotransferase IV in a final volume of 30 fiL. The reaction was initiated by addition of enzyme. After 30 minutes of incubation, the reaction was terminated by adding 30 fiL of methanol and 

Aryl sulfotransferase IV (AST IV) was purified to apparent homogeneity from the livers of rats. 

Cysteine conjugate /3-lyases cleave the carbon-sulfur bond of S-substituted L-cysteine conjugates via a -elimination reaction to produce pyruvate, ammonia, and the corresponding thiols. These enzymes are found in kidney, liver 

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King RS, Sharma V, Pedersen LC, Kakuta Y, Negishi M, Duffel MW. Structure-function modeling of the interactions of the A-alkyl-A-hydroxyanilines with rat hepatic aryl sulfotransferase IV. Chem Res Toxicol 2000 13 1251-8. 

It has been proposed that 8-aminodcoxyguanosinc is formed from the nitronate tautomer of 2-nitropropane either by base nitrosation followed by reduction, or via an enzyme-mediated conversion of the nitronate anion to hydroxyiam ine-O-sulfonate or acetate, which yields the highly reactive nitrenium ion NHj (Sodum et al., 1993). Sodum et al. (1994) have provided evidence for the activation of 2-nitropropane to an aminating species by rat liver aryl sulfotransferase in vitro and in vivo. Pretreatment of rats with the aryl sulfotransferase inhibitors pentachlorophenol or 2,6-dichloro-4-nitrophenol significantly decreased the levels of nucleic acid modifications produced in the liver by 2-nitropropane treatment. Partially purified rat liver aryl sulfotransferase activated 2-nitropropane and its nitronate at neutral pH to a reactive species that aminated guanosine at the position. This activation was dependent on the presence of the enzyme, its specific cofactor adenosine 3 -phosphate 5 -phosphosulfate, and mercaptoethanol. It was inhibited... 

Fiala, E.S., Sodum, R.S., Hussain, N.S., Rivenson, A. Dolan, L. (1995) Secondary nitroalkanes induction of DNA repair in rat hepatocytes, activation by aryl sulfotransferase and hepatocarcinogenicity of 2-nitrobutane and 3-nitropentane in male F344 rats. Toxicology, 99, 89-97... 

Figure 9.146 HPLC analysis of PAP in an aryl sulfotransferase IV reaction mixture. The reaction mixture and incubation conditions were 50 fiM 1-naphthalenemethanol and 2.9 fig of AST IV. The mobile phase for HPLC analysis contained 12% methanol in 75 mM potassium phosphate (pH 5.45), 100 mM ammonium chloride, and 1.0 mM 1-octylamine. The flow rate was 2.0 mL/min, and detection was at 254 nm, with a full scale sensitivity of 0.02 AU. Sample injection is indicated by an arrow. (From Duffel et al., 1989.)...

The sulfotransferases have been divided into several groups as a result of substrate specificity determinations with purified enzymes and molecular biology studies aryl sulfotransferases are active toward phenols, hydroxylamines, tyrosine esters, and catecholamines alcohol sulfotransferases are active toward primary and secondary steroid alcohols and amine sulfotransferases are active toward arylamines. 

Introduction. Sulfation reactions consist of a sulfate being transferred from the cofactor 3 -phosphoadenosine 5 -phosphosulfate (19) (PAPS Fig. 13.17)to the substrate under catalysis by a sulfotransferase. The three criteria of conjugation are met in these reactions. Sulfotransferases, which catalyze a variety of physiological reactions, are soluble enzymes that include aryl sulfotransferase (phenol sulfotransferase EC 2.8.2.1), alcohol sulfotransferase (hydroxysteroid sulfotransferase EC... 

Duanmu, Z., Dunbar, J., Falany, C. N., and Runge-Morris, M. (2000) Induction of rat hepatic aryl sulfotransferase (SULT1A1) gene expression by triamcinolone acetonide impact on minoxidil-mediated hypotension. Toxicol. Appl. Pharmacol. 164, 312-320. 

Toxicol., 13, 1251 (2000). Structure-Function Modeling of the Interactions of the N-alkyl-N-Hydroxyanilines with Rat Hepatic Aryl Sulfotransferase IV. 

Analysis of Substrates for an Aryl Sulfotransferase Based on Catalytic Mechanism and Protein Homology Modeling. 

Gilissen, R. A. H. J., D. R Ringer, H. J. F. C, Stavenuiter, G. J. Mulder and J. H. N. Meerman. 1992. Sulfation of hydroxy lamines and hydroxamic acids in liver cytosol from male and female rats and purified aryl sulfotransferase IV. Carcinogenesis 13 1699-1703. 

Mangold, B. L. K., J. Erickson, C. Lohr, D. J. McCann and J. B. Mangold. 1990. Self-catalyzed irreversible inactivation of rat hepatic aryl sulfotransferase IV by N-hydroxy-2-acetylaminofluorene. Carcinogenesis 11 1563-1567. 

Ringer, D. R, T. R. Norton and R. R. Self. 1992. Reaction product inactivation of aryl sulfotransferase IV following electrophilic substitution by the sulfuric acid ester of N-hydroxy-2-acetylaminofluorene. Carcinogenesis 13 107-112. 

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