title: Effects of caffeine on stereoselectivities of high cell density biotransformations of cyclic beta-keto esters with Saccharomyces cerevisiae.
abstract: Caffeine affects the stereoselectivity of microbial high cell density reductions with commercial grade Saccharomyces cerevisiae (Baker's yeast). Cyclic beta-keto esters ethyl 2-oxocyclopentanoate (1) and ethyl 2-oxocyclohexanoate (3) were shown to be reduced with increased diastereoselectivity (1: 90.1 --> 92.1% de, 3: 75.0 --> 90.0% de) after addition of caffeine. Effects on enantioselectivity were less pronounced (1: 97.3 --> 98.5% ee, 3: 90.1 --> 92.1% ee). The observations are ascribed to the action of caffeine on cellular calcium homeostasis. These effects are accompanied by caffeine-induced cell-death, which preferably takes effect on pre-stressed cells which were found to decrease diastereoselectivity.
authors.affiliation: Institute of Biochemistry, Dresden University of Technology, Dresden, D-01062, Germany.
authors.forename: Mathilde
authors.initials: M
authors.lastname: Bohn
authors.forename: Kathrin
authors.initials: K
authors.lastname: Leppchen
authors.forename: Michael
authors.initials: M
authors.lastname: Katzberg
authors.forename: Alexander
authors.initials: A
authors.lastname: Lang
authors.forename: Juliane
authors.initials: J
authors.lastname: Steingroewer
authors.forename: Jost
authors.initials: J
authors.lastname: Weber
authors.forename: Thomas
authors.initials: T
authors.lastname: Bley
authors.forename: Martin
authors.initials: M
authors.lastname: Bertau
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001711:Biotransformation / Q000187:drug effects; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000737:chemistry; D002452:Cell Count; D003500:Cyclization; D004952:Esters / Q000737:chemistry* / Q000378:metabolism; D007659:Ketones / Q000737:chemistry* / Q000378:metabolism; D008274:Magnesium / Q000737:chemistry; D015394:Molecular Structure; D010084:Oxidation-Reduction; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000378:metabolism*; D013237:Stereoisomerism
chemical_list: D004952:Esters; D007659:Ketones; D002110:Caffeine; D008274:Magnesium; D002118:Calcium