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Enantioselective Sulfoxidation Catalyzed by Vanadium Haloperoxidases
Hilda B. ten Brink1, Antonin Tuynman, Henk L. Dekker
1E. C. Slater Institute, BioCentrum, University of Amsterdam, Plantage Muidergracht 12, 1018 TV Amsterdam, The Netherlands, Department of Biotechnology, Faculty of Engineering, Tottori University, Tottori 680, Japan, DSM Research, Bio-Organic Chemistry, P.O. Box 18, 6160 MD Geleen, The Netherlands.
Inorganic Chemistry
|October 24, 2001
Summary
Vanadium haloperoxidases can enantioselectively oxidize organic sulfides to sulfoxides. Different vanadium enzymes yield specific enantiomers, with one achieving 91% selectivity for the (R)-sulfoxide.
Area of Science:
- Biochemistry
- Enzymology
- Organic Chemistry
Background:
- Vanadium haloperoxidases are enzymes known for catalyzing halide oxidation.
- These enzymes utilize hydrogen peroxide to produce hypohalous acid.
- Their potential in mediating other oxidation reactions is less explored.
Purpose of the Study:
- To investigate the enantioselective oxidation of organic sulfides mediated by vanadium haloperoxidases.
- To determine the stereochemical outcome of sulfoxidation reactions catalyzed by different vanadium haloperoxidases.
- To assess the influence of enzyme source and reaction conditions on enantioselectivity.
Main Methods:
- Incubation of organic sulfides (methyl phenyl sulfide, methyl p-tolyl sulfide, 1-methoxy-4 (methylthio)benzene) with vanadium haloperoxidases.
- Analysis of reaction products for yield and enantiomeric excess (ee) of sulfoxides using techniques like chiral chromatography.
- Optimization of reaction conditions, including pH and hydrogen peroxide concentration.
Main Results:
- Vanadium bromoperoxidase from Ascophyllum nodosum produced (R)-sulfoxides with up to 85% ee and 91% selectivity at low peroxide concentrations.
- Vanadium bromoperoxidase from Corallina pilulifera yielded (S)-sulfoxides with 55% ee.
- Vanadium chloroperoxidase from Curvularia inaequalis produced a racemic mixture of sulfoxides.
Conclusions:
- Vanadium haloperoxidases exhibit enantioselective capabilities in sulfoxidation reactions.
- The source of the vanadium haloperoxidase dictates the stereochemical outcome of the reaction.
- These enzymes offer a biocatalytic route for synthesizing enantiomerically enriched sulfoxides.