The use of alkene reductases for stereoselective C=C bond reduction has become an increasingly useful synthetic method. We have created a collection of overexpressed flavoprotein alkene reductases from the Old Yellow Enzyme (OYE) family and evaluated their performance against a library of diverse alkene substrates. While the resulting products often possessed high optical purities, there was little or no difference in the enzymes' enantiopreferences. This is a serious drawback for organic synthesis, where access to both product stereoisomers is essential. We have used protein engineering approaches to address this limitation. Our ability to determine experimental structures for OYE-substrate complexes by X-ray crystallography has been an essential tool in this project. This talk will focus on our recent progress in the area that has included mutants with reversed enantioselectivities for both (R)- and (S)-carvone1 and Baylis-Hillman adducts.2 In addition, some preliminary applications of OYE for preparative-scale alkene reductions will also be discussed.3
Enone substrate bound within the active site of W116I Saccharomyces pastorianus OYE1.
References
1) Padhi, S.K., Bougioukou, D.J., Stewart, J.D. (2009), J. Am. Chem. Soc. 131 3271-3280.
2) Walton, A.Z., Conerly, W.C., Pompeu, Y.A., Sullivan, B., Stewart, J.D. (2011) ACS Catalysis, 1, 989-993.
3) Bougioukou, D.J., Walton, A.Z., Stewart, J.D. (2010) Chem. Commun. 46, 8558-8560.