99.5, 98.2, and 96.0 %, respectively) and specific activities up to 16 U g cdw −1. coli BL21 (DE3) is one of the most promising biocatalysts described so far and converted sulfides 1, 3, and 9 to respective ( R)-sulfoxides with remarkable enantioselectivities (e.e. Thus, improving described systems or identifying novel ones is still necessary. 11 However, (enantio)selectivity, versatility with respect to the structural diversity of accepted prochiral sulfides, as well as activity and stability of respective biocatalysts are properties, which often hinder industrial application. 11Ī number of enzymes such as cytochrome P450 monooxygenases, 12 Baeyer-Villiger monooxygenases (BVMOs), 13, 14 peroxidases, 15 and styrene monooxygenases (SMOs) 16 among others catalyze regio- and enantioselective sulfoxidation, which has been pioneered by work on peroxidases and BVMOs. 5 The latter can be accomplished by the application of chemical 2, 10 or biological catalysts, with the biocatalysts typically having a selectivity advantage. This can be achieved by costly and labor intensive resolution of racemates 9 or direct asymmetric synthesis. 4, 5 As the potency of one enantiomer often outperforms the one of the antipode (e. g., shown for esomeprazole), 6- 8 enantiopure sulfoxide preparation is required. With its extraordinarily high specific activity, high specificity, ease of handling, and high stability (catalyst is stable for >16 days at 4 ☌), the designed whole-cell biocatalyst adds enormous value to the portfolio of chemical and biological catalysts for asymmetric sulfoxide synthesis.Ĭhiral sulfoxides have gained huge attention as synthons and precursors for the synthesis of APIs, 1, 2 flavors and fragrances, 3 or as chiral auxiliaries in chemical syntheses. The formulation as a whole-cell biocatalyst allowed specific production rates of up to 370 U g cdw −1 – the highest specific oxygenase activity achieved in whole cells so far – and the preparative synthesis of enantiopure ( S)-aryl alkyl sulfoxides. Next to indole and styrene, AbIMO was found to accept numerous alkyl aryl sulfides as substrates, transforming them to ( S)-sulfoxides with high enantioselectivity (95 % to >99 % for most sulfides).

coli and characterized for its sulfoxidation activity and substrate spectrum. Here, AbIMO was expressed recombinantly in E. The flavoprotein monooxygenase AbIMO from Acinetobacter baylyi ADP1 initiates indole degradation. Flavoproteins such as Baeyer-Villiger or styrene monooxygenases mainly provide access to ( R)-sulfoxides and often suffer from low selectivity, activity, and/or limited substrate scope. Chiral sulfoxides have gained attention as synthons and precursors for API synthesis.

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