Semisynthetic enzymes in asymmetric synthesis:: Enantioselective reduction of racemic hydroperoxides catalyzed by seleno-subtilisin

The serine protease subtilisin was chemically converted into the peroxidase-active seleno-subtilisin. This semisynthetic enzyme catalyzes the enantioselective reduction of racemic hydroperoxides in the presence of thiophenols to yield optically active hydroperoxides and alcohols on the semipreparative scale. The kinetic parameters and enantioselectivities of seleno-subtilisin-catalyzed reduction of various chiral hydroperoxides were determined. The catalytic efficiency of this semisynthetic enzyme is comparable to that of the native horseradish peroxidase. The sense in the enantioselectivity of the seleno-subtilisin is opposite to the natural enzymes previously used in the synthesis of optically active hydroperoxides. Consequently, the semisynthetic enzyme selenosubtilisin complements the naturally available peroxidases for the asymmetric synthesis of both enantiomers.