Enantioselective Sulfoxidation Catalyzed by Vanadium Haloperoxidases.
Vanadium haloperoxidases catalyze the oxidation of halides by hydrogen peroxide to produce hypohalous acid. We demonstrate that these enzymes also slowly mediate the enantioselective oxidation of organic sulfides (methyl phenyl sulfide, methyl p-tolyl sulfide, and 1-methoxy-4 (methylthio)benzene) to the corresponding sulfoxides (turnover frequency 1 min(-)(1)). The vanadium bromoperoxidase from the brown seaweed Ascophyllum nodosum converts methyl phenyl sulfide to the (R)-enantiomer of the sulfoxide (55% yield and 85% enantiomeric excess (ee)). At low peroxide concentrations a selectivity of 91% can be attained. The enzyme catalyzes the selective sulfoxidation reaction over a broad pH range with an optimum around pH 5-6 and remains completely functional during the reaction. When the vanadium bromoperoxidase from the red seaweed Corallina pilulifera is used the (S)-enantiomer (18% yield and 55% ee) is formed. In contrast, the vanadium chloroperoxidase from the fungus Curvularia inaequalis catalyzes the production of a racemic mixture (54% yield), which seems to be an intrinsic characteristic of this enzyme.
ten Brink
Hilda B.
HB
E. 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.
Tuynman
Antonin
A
Dekker
Henk L.
HL
Hemrika
Wieger
W
Izumi
Yoshikazu
Y
Oshiro
Takashi
T
Schoemaker
Hans E.
HE
Wever
Ron
R