Record number :
1617640
Title of article :
New strategies improve the efficiency of the bakerʹs yeast reduction of ketoesters: near UV irradiation and a two-substrate application
Author/Authors :
Ute Vitinius، نويسنده , , Ute and Schaffner، نويسنده , , Kurt and Demuth، نويسنده , , Martin، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2005
Pages :
14
From page :
197
To page :
210
Abstract :
The stereodifferentiation of the bakerʹs yeast reduction of β-ketoesters is improved by exposing this reaction to 300–400 nm UV light and via a new method entitled ‘two-substrate application’. Both routes are accomplished by selectively interfering with those oxidoreductases that compete for the same substrate. While the irradiation enhances the enantioselectivity of the bakerʹs yeast upon reducing the substrate 3-oxo-n-valeric ethylester inhibits it the conversion of ethyl acetoacetate, whereas other homologues are not influenced. Corresponding in vitro reductions with the bakerʹs yeast enzymes alcohol dehydrogenase I (ADH I), l-lactate dehydrogenase (l-LDH), and β-ketoacylreductase are light-resistant, whereby the l-LDH reacts in the presence of β-nicotinamide adenine dinucleotide (NADH). The catalytic activity of pre-irradiated ADH I is reduced because the light changes the conformation of the isolated enzyme according to CD spectroscopy. The natural enzyme cofactor NADH protects the ADH I in the in vitro reduction experiment from the near UV light by absorbing it for conducting its own photochemistry. In the bakerʹs yeast reduction of ethyl acetoacetate, apparently four oxidoreductases compete for this substrate.
Keywords :
UV light protection , Bakerיs yeast , ?-Ketoacylreductase , l-Lactate dehydrogenase (l-LDH) , Reduction of ketoesters , ?-NADH , Two-substrate application , biotransformation , Circular dichroism (CD) , Light enhancement , Bakerיs yeast oxidoreductases: alcohol dehydrogenase I (ADH I) , photochemistry
Journal title :
Journal of Photochemistry and Photobiology:A:Chemistry
Serial Year :
2005
Link To Document :
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