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Asymmetric sulfoxidations mediated by alpha-chymotrypsin
Prasanta Kumar Das1, Jose M M Caaveiro, Susana Luque
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Biotechnology and Bioengineering
|February 22, 2002
Summary
The enzyme alpha-chymotrypsin accelerates sulfide oxidation using hydrogen peroxide (H2O2), achieving stereoselective production of sulfoxides. This asymmetric catalysis occurs within the enzyme's hydrophobic active site pocket.
Area of Science:
- Biocatalysis
- Enzyme kinetics
- Organic chemistry
Background:
- Sulfide oxidation with H2O2 typically yields racemic mixtures.
- Enzymatic catalysis offers potential for stereoselective synthesis.
Purpose of the Study:
- To investigate the stereoselective oxidation of aryl alkyl sulfides using alpha-chymotrypsin.
- To elucidate the mechanism of enzyme-mediated asymmetric sulfoxidation.
Main Methods:
- Utilized hydrogen peroxide (H2O2) for sulfide oxidation in aqueous solution.
- Employed the hydrolytic enzyme alpha-chymotrypsin as a biocatalyst.
- Applied structure-based molecular modeling to analyze enzyme-sulfide interactions.
Main Results:
- Alpha-chymotrypsin significantly accelerated the sulfoxidation reaction.
- The enzyme-mediated oxidation demonstrated high stereoselectivity, producing enantiomerically enriched sulfoxides.
- Phenyl isobutyl sulfide oxidation occurred within the enzyme's hydrophobic binding pocket.
Conclusions:
- Alpha-chymotrypsin effectively catalyzes asymmetric sulfoxidation.
- The enzyme's hydrophobic active site pocket is crucial for achieving stereoselectivity.
- Molecular modeling accurately explains the observed stereochemical outcomes.