作者: Bennett Ma , Magang Shou , Michael L. Schrag
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摘要: Sulfation is an important reaction in the biotransformation of steroid hormones, neurotransmitters, drugs, and other xenobiotics, yet little known about effects organic solvents on sulfotransferase (SULT) activities vitro. Initial experiments found that surprisingly low levels solvent had dramatic activity. Consequently, we evaluated five commonly used (methanol, ethanol, acetonitrile, dimethyl sulfoxide, formamide) cDNA-expressed isozymes 1A1 (4-nitrophenol sulfation), 1A3 (dopamine 1E1 (ethynylestradiol 2A1 (dehydroepiandrosterone sulfation). In addition, 1-hydroxypyrene was as a general fluorescent probe for all four isoforms examined. When substrates were present at their respective isoform-specific Km values, methanol ethanol (0.4%, v/v) generally less effect than formamide activities. Acetonitrile, cytochrome P450 studies, inhibited SULT1A1 (∼40%) 0.4% (v/v), but activated SULT1E1-mediated sulfation ∼2.6-fold. Assuming two-site kinetic model, studies revealed affected Vmax1,Vmax2, Ki value mediated by SULT1E1. contrast, not affected, suggesting may potentially alter binding interactions second substrate molecule, first. Additional with expressed SULT1A1, supplemented control protein, inhibitory reduced to 12 μg/ml total protein.