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- Title
Exploitation of a Laccase/Meldola's Blue System for NAD<sup>+</sup> Regeneration in Preparative Scale Hydroxysteroid Dehydrogenase-Catalyzed Oxidations.
- Authors
Ferrandi, Erica Elisa; Monti, Daniela; Patel, Ilabahen; Kittl, Roman; Haltrich, Dietmar; Riva, Sergio; Ludwig, Roland
- Abstract
An enzymatic regeneration system consisting of laccase and the 2H+/2e− redox mediator Meldola's blue (MB) was developed for the efficient oxidation of reduced nicotinamide adenine dinucleotide (NADH) cofactor and employed in the gram-scale oxidation of cholic acid ( 1) to its 7-keto derivative ( 1a) by 7α-hydroxysteroid dehydrogenase (7α-HSDH) in an aqueous, buffered reaction system. The regenerating enzyme, laccase, reduces molecular oxygen as terminal 4H+/4e− acceptor to water and concomitantly reoxidizes NADH via MB at high turnover rates. The regeneration system was successfully applied to quantitatively convert 1 (50 mM, 20.4 g) into 1a with a space-time yield of 5.8 mmol L−1 h−1. High total turnover numbers were achieved for 7α-HSDH (4.2×105) and laccase (1.1×106). Alternatively, the regeneration system was employed on the conversion of the methyl ester derivative of cholic acid ( 2, 200 mM, 5.9 g) dissolved in isopropyl acetate as organic solvent in a biphasic system. Due to the high concentration of 2 and the excellent performance of the enzymatic cascade reaction even under the harsh process conditions, space-time yields of up to 20 mmol L−1 h−1 (8.5 g L−1 h−1) of the produced 7-keto derivative 2a were obtained. The irreversibility and high driving force of the regenerating reaction allowed quantitative conversions and easy product recovery.
- Publication
Advanced Synthesis & Catalysis, 2012, Vol 354, Issue 14/15, p2821
- ISSN
1615-4150
- Publication type
Article
- DOI
10.1002/adsc.201200429