In Vitro Double Oxidation of n-Heptane with Direct Cofactor Regeneration.

Autor: Müller, Christina A., Akkapurathu, Beneeta, Winkler, Till, Staudt, Svenja, Hummel, Werner, Gröger, Harald, Schwaneberg, Ulrich
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Zdroj: Advanced Synthesis & Catalysis; Jun2013, Vol. 355 Issue 9, p1787-1798, 12p
Abstrakt: A novel concept for the direct oxidation of cycloalkanes to the corresponding cyclic ketones in a one-pot synthesis in water with molecular oxygen as sole oxidizing agent was reported recently. Based on this concept we have developed a new strategy for the double oxidation of n-heptane to enable a biocatalytic resolution for the direct synthesis of heptanone and ( R)-heptanols in a one-pot reaction. The bicatalytic cascade employs an NADH driven P450 BM3 monooxygenase variant (WTNADH, 19A12NADH or CM1NADH) and an ( S)-enantioselective alcohol dehydrogenase (RE-ADH). In the initial step n-heptane is hydroxylated under consumption of NADH to produce ( R/ S)-heptanol. In the second oxidation step the ( S)-heptanol enantiomers are transformed to the corresponding ketones, reducing and thereby regenerating the cofactor. Characterization of initial hydroxylation step revealed high turnover frequencies (TOF) of up to 600 min−1, as well as high coupling efficiencies using NADH as cofactor (up to 44%). In the cascade reaction a nearly 2-fold improved product formation was achieved, compared to the single hydroxylation reaction. The total product concentration reached 1.1 mM, corresponding to a total turnover number (TTN) of 2500. Implementation of an additional cofactor regeneration system ( D-glucose/glucose dehydrogenase) enabled a further enhancement in product formation with a total product concentration of 1.8 mM and a TTN of 3500. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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