. Author manuscript; available in PMC: 2017 Jun 1.

Published in final edited form as: Phytochem Rev. 2016 Mar 11;15(3):425–444. doi: 10.1007/s11101-016-9459-z

Table 3.

Protein functional motifs and classification of the principal reductases involved in the conversion of daidzein to (S)-equol (Schroder, Matthies, Engst et al., 2013)

Enzyme	Proposed Classification	Functional sequence motifs
Daidzein reductase (DZNR)	Old yellow enzyme (OYE) family; NADH:flavin oxidoreductase family (Karplus, Fox, Massey, 1995)	CX₂CX₃CX₁₂C: 4Fe-4S cluster binding motif hhhXGXGX₂GXE (where h is a hydrophobic residue): extended dinucleotide binding motif
Dihyrodaidzein reductase (DHDR)	“Classical” short-chain dehydrogenases/reductase (SDR) family (Kavanagh, Jornvall, Persson et al., 2008; Oppermann, Filling, Hult et al., 2003)	YX₃K : catalytic tetrad TGX₃GXG: conserved dinucleotide-binding motif;
Tetrahydrodaidzein reductase (THDR)	Glycyl radical enzyme family (Buckel, Golding, 2006; Shisler, Broderick, 2014)	GXGX₂G: N-terminal dinucleotide-binding motif RVXG: glycyl radical enzyme motif