Conversion of (3S,4R)-tetrahydrodaidzein to (3S)-equol by THD reductase: proposed mechanism involving a radical intermediate.
To elucidate the mechanism of (3S)-equol biosynthesis, (2,3,4-d(3))-trans-THD was synthesized and converted to (3S)-equol by THD reductase in Eggerthella strain Julong 732. The position of the deuterium atoms in (3S)-equol was determined by (1)H NMR and (2)H NMR spectroscopy, and the product was identified as (2,3,4(alpha)-d(3))-(3S)-equol. All the deuterium atoms were retained, while the OH group at C-4 was replaced by a hydrogen atom with retention of configuration. To explain the deuterium retention in this stereospecific reduction, we propose a mechanism involving radical intermediates.
Kim
Mihyang
M
Metalloenzyme Research Group and Department of Biotechnology, Chung-Ang University, Anseong 456-756, Korea.
Marsh
E Neil G
EN
Kim
Soo-Un
SU
Han
Jaehong
J
D001421:Bacteria, Anaerobic / Q000378:metabolism*; D003903:Deuterium; D060754:Equol; D005609:Free Radicals / Q000378:metabolism; D007529:Isoflavones / Q000096:biosynthesis* / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D055601:Organic Chemistry Phenomena; D010088:Oxidoreductases / Q000378:metabolism*; D013237:Stereoisomerism
D005609:Free Radicals; D007529:Isoflavones; C433164:tetrahydrodaidzein; D060754:Equol; D003903:Deuterium; D010088:Oxidoreductases