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34S isotope effect on sulfate ester hydrolysis: mechanistic implications.
Benjamin T Burlingham1, Lisa M Pratt, Ernest R Davidson
1Department of Chemistry, Indiana University, Bloomington, IN 47405, USA.
Journal of the American Chemical Society
|October 23, 2003
Summary
This study reports the first 34S kinetic isotope effects (KIEs) for sulfate monoester hydrolysis. The findings challenge associative mechanisms and offer a new method for studying sulfuryl group transfers.
Area of Science:
- Biochemistry
- Chemical Kinetics
- Isotope Chemistry
Background:
- Sulfate monoester hydrolysis is crucial in biological and chemical processes.
- Understanding the hydrolysis mechanism is key to enzyme function and reaction pathway elucidation.
- Kinetic isotope effects (KIEs) provide valuable mechanistic insights.
Purpose of the Study:
- To report the first determination of 34S KIEs for sulfate monoester hydrolysis.
- To investigate the hydrolysis mechanism of sulfate monoesters using KIEs.
- To establish a novel isotope effect method for sulfuryl group transfer reactions.
Main Methods:
- Hydrolysis of sulfate monoesters (p-nitrophenyl sulfate, p-acetylphenyl sulfate).
- Conversion of inorganic sulfate to sulfur dioxide (SO2).
- Isotope ratio determination using mass spectrometry.
Main Results:
- Determined 34S KIEs for p-nitrophenyl sulfate (1.0154 ± 0.0002) and p-acetylphenyl sulfate (1.0172 ± 0.0003).
- Results are inconsistent with a proposed associative mechanism when combined with existing 18O KIE data.
- Demonstrated the utility of the developed isotope effect method.
Conclusions:
- The hydrolysis mechanism of sulfate monoesters is likely not associative.
- The reported 34S KIE method is a valuable tool for mechanistic studies of sulfuryl group transfers.
- This method can be applied to sulfatase, sulfotransferase, and other sulfate hydrolysis reactions.
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