Stereoselective oxidation of aliphatic diols and reduction of hydroxy-ketones with galactitol dehydrogenase from Rhodobacter sphaeroides D

From the Rhodobacter sphaeroides mutant D a galactitol dehydrogenase (GDH) was isolated and characterized in an earlier investigation (1). The enzyme expressed activity with a wide spread substrate spectrum, like sugars, sugar alcohols, secondary alcohols or the corresponding ketones and it can be u...

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Bibliographic Details
Published inCommunications in agricultural and applied biological sciences Vol. 68; no. 2 Pt A; p. 309
Main Authors Kohring, G W, Wiehr, P, Jeworski, M, Giffhorn, F
Format Journal Article
LanguageEnglish
Published Belgium 2003
Subjects
Dihydroxydihydrobenzopyrenes - pharmacokinetics
Ketones - metabolism
Kinetics
Oxidation-Reduction
Rhodobacter sphaeroides - enzymology
Rhodobacter sphaeroides - growth & development
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
Substrate Specificity
Sugar Alcohol Dehydrogenases - metabolism
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Summary:From the Rhodobacter sphaeroides mutant D a galactitol dehydrogenase (GDH) was isolated and characterized in an earlier investigation (1). The enzyme expressed activity with a wide spread substrate spectrum, like sugars, sugar alcohols, secondary alcohols or the corresponding ketones and it can be used for the production of the rare sugar L-tagatose by regioselective oxidation of galactitol (2). This study focuses on the preparation of optically pure aliphatic diols by oxidation of one enantiomer or stereospecific reduction of keto-alcohols and diketones. The oxidation of 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol and 1,2-hexanediol occurred highly specific with the S-enantiomer leaving the R-enantiomer of the diols in the reaction vessel. Also (S)-1,2,6-hexanetriol was oxidized by GDH to 1,6-dihydroxy-2-hexanone. The Km values of these reactions decreased with increasing length of the carbon chain. Reduction of hydroxyacetone or 1-hydroxy-2-butanone resulted in an excess of 93% (S)-1,2-propanediol and more than 98% of (S)-1,2-butanediol, respectively. The diketone 2,3-hexanedione was only reduced to (2R,3S)-2,3-hexanediol, one of the possible four configurations. The wide substrate spectrum on one hand and the selectivity in the reaction on the other hand make GDH a very interesting enzyme for the production of optically pure building blocks in the chemical synthesis of bioactive compounds.
ISSN:1379-1176