Journal of the American Chemical Society · 2003 · 25 citations · 6 references
Natural SciencesBiochemistryChemistryChemical KineticsEnzymologyMass Spectrometric AnalysisEnzyme KineticsKinetic Isotope EffectsStable Isotope AnalysisSulfur ChemistrySulfur CompoundsSulfur DioxideHydrolysisIsotope Ratio AnalysisIsotopic Ratio DeterminationMass Ratio DeterminationSulfate ChemistrySulfotransferase ActivitySulfur Isotope AnalysisSulfur Metabolism Enzymes
In this communication, we report the first determination of 34S kinetic isotope effects (KIEs) for the hydrolysis of sulfate monoesters. The method involves the conversion of the inorganic sulfate, acquired at partial extent of reaction, to SO2, followed by isotope ratio determination by mass spectrometry. The KIEs determined for p-nitrophenyl sulfate and p-acetylphenyl sulfate are 1.0154 (+/-0.0002) and 1.0172 (+/-0.0003), respectively. These results, together with previous peripheral 18O KIE values, are inconsistent with an associative mechanism. The isotope effect method we report should also prove useful for studying the mechanism of other sulfuryl group transfers, including sulfatase and sulfotransferase reactions, as well as sulfate hydrolyses under other conditions.
6