Stereoselective multi-step reduction of dehydrocholic acid with hydroxysteroid dehydrogenases

Boqiao Sun, doctoral thesis Technische Universität München, 2014

The two-step reduction of dehydrocholic acid to 12-keto-ursodeoxycholic acid is the biocatalytic step in the chemo-enzymatic synthesis of ursodeoxycholic acid. Escherichia coli whole-cell biocatalysts expressing hydroxysteroid dehydrogenases were designed to enable a simple biocatalytic one-pot process. The process was analyzed and optimized through modeling. When applying even low amounts of the whole cell biocatalyst on a liter-scale,  28 g/L dehydrocholic acid could be completely converted to the desired pure chiral product and high space-time yields of 120 g/L/d were achieved.


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