The invention provides a
mutant of 7 beta-hydroxyl
steroid dehydrogenase, application of the
mutant and a synthesis method. The
mutant of the 7 beta-hydroxyl
steroid dehydrogenase is characterized in that
amino acid sequences of the mutant are Seq ID NO:4, and coded
nucleotide sequences are Seq ID NO:3; or
amino acid sequences of the mutant are Seq ID NO:6, and coded
nucleotide sequences are Seq ID NO:5. The mutant, the application and the synthesis method have the advantages that
cholic acid compounds, particularly
ursodeoxycholic acid, can be catalytically synthesized by the efficient 7 beta-hydroxyl
steroid dehydrogenase, mutant enzymes of the 7 beta-hydroxyl
steroid dehydrogenase and coenzyme regeneration systems, accordingly, the
substrate concentration can reach 100 g / L, the conversion rate is 99.2-99.5%, and the weight yield can reach 94-96%; and the enzymes can be inexpensively and easily obtained by the aid of a
fermentation process, accordingly, the production cost and the product quality are superior to the production cost and the product quality of
chemical synthesis methods, and the mutant and the synthesis method are applicable to industrial production.