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 1H NMR and 2H NMR spectroscopy, and the product was identifi...

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Bibliographic Details
Published in:Biochemistry (Easton) 2010-07, Vol.49 (26), p.5582-5587
Main Authors: Kim, Mihyang, Marsh, E. Neil G, Kim, Soo-Un, Han, Jaehong
Format: Article
Language:English
Subjects:
Bacteria, Anaerobic - metabolism
Deuterium
Equol
Free Radicals - metabolism
Isoflavones - biosynthesis
Isoflavones - metabolism
Magnetic Resonance Spectroscopy
Molecular Conformation
Organic Chemistry Phenomena
Oxidoreductases - metabolism
Stereoisomerism
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Summary: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 1H NMR and 2H NMR spectroscopy, and the product was identified as (2,3,4α-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.
ISSN:0006-2960
1520-4995
DOI:10.1021/bi100465y