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Literature Information

Title	Identification of a Novel Dihydrodaidzein Racemase Essential for Biosynthesis of Equol from Daidzein in Lactococcus sp. Strain 20-92
Author	Yoshikazu Shimada, Masayuki Takahashi, Norihiro Miyazawa, Yasuhiro Abiru, Shigeto Uchiyama, Haretsugu Hishigaki
DOI	10.1128/AEM.00410-12
Abstract	Equol is metabolized from daidzein, a soyisoflavone, by the gut microflora. In this study, we identified a novel dihydrodaidzein racemase (l-DDRC) that is involved in equol biosynthesis in a lactic acid bacterium, Lactococcus sp. strain 20-92, and confirmed that histidine-tagged recombinant l-DDRC (l-DDRC-His) was able to convert both the (R)- and (S)-enantiomers of dihydrodaidzein to the racemate. Moreover, we showed that recombinant l-DDRC-His was essential for in vitro equol production from daidzein by a recombinant enzyme mixture and that efficient in vitro equol production from daidzein was possible using at least four enzymes, including l-DDRC. We also proposed a model of the metabolic pathway from daidzein to equol in Lactococcus strain 20-92.