Reaction: a (4R)-4,2'-dihydroxyisoflavan = a pterocarpan + H2O
For diagram of reaction click here
Glossary: an isoflavan = an isoflavonoid with a 3,4-dihydro-3-aryl-2H-1-benzopyran skeleton.
(-)-medicarpin = (6aR,11aR)-9-methoxy-6a,11a-dihydro-6H-benzofuro[3,2-c]chromen-3-ol
(+)-medicarpin = (6aS,11aS)-9-methoxy-6a,11a-dihydro-6H-benzofuro[3,2-c]chromen-3-ol
(-)-maackiain = (6aR,12aR)-6a,12a-dihydro-6H-[1,3]dioxolo[5,6]benzofuro[3,2-c]chromen-3-ol
(+)-maackiain = (6aS,12aS)-6a,12a-dihydro-6H-[1,3]dioxolo[5,6]benzofuro[3,2-c]chromen-3-ol
(+)-pterocarpan = (6aR,11aR)-6a,11a-dihydro-6H-benzofuran[3,2-c]benzopyran
Other name(s): medicarpin synthase; medicarpan synthase; 7,2'-dihydroxy-4'-methoxyisoflavanol dehydratase; 2',7-dihydroxy-4'-methoxyisoflavanol dehydratase; DMI dehydratase; DMID; 2'-hydroxyisoflavanol 4,2'-dehydratase; PTS (gene name); 4'-methoxyisoflavan-2',4,7-triol hydro-lyase [(-)-medicarpin-forming]
Systematic name: (4R)-4,2'-dihydroxyisoflavan hydro-lyase (pterocarpan-forming)
Comments: The enzyme catalyses the formation of the additional ring in pterocarpan, the basic structure of phytoalexins produced by leguminous plants, including (-)-medicarpin, (+)-medicarpin, (-)-maackiain and (+)-maackiain. The enzyme requires that the hydroxyl group at C-4 of the substrate is in the (4R) configuration. The configuration of the hydrogen atom at C-3 determines whether the pterocarpan is the (+)- or (-)-enantiomer. The enzyme contains amino acid motifs characteristic of dirigent proteins.
Links to other databases: BRENDA, EXPASY, ExplorEnz, IUBMB, KEGG, MetaCyc, CAS registry number:
1. Guo, L., Dixon, R.A. and Paiva, N.L. The ‘pterocarpan synthase’ of alfalfa: association and co-induction of vestitone reductase and 7,2'-dihydroxy-4'-methoxy-isoflavanol (DMI) dehydratase, the two final enzymes in medicarpin biosynthesis. FEBS Lett. 356 (1994) 221-225. [PMID: 7805842]
2. Guo, L., Dixon, R.A. and Paiva, N.L. Conversion of vestitone to medicarpin in alfalfa (Medicago sativa L.) is catalyzed by two independent enzymes. Identification, purification, and characterization of vestitone reductase and 7,2'-dihydroxy-4'-methoxyisoflavanol dehydratase. J. Biol. Chem. 269 (1994) 22372-22378. [PMID: 8071365]
3. Uchida, K., Akashi, T. and Aoki, T. The missing link in leguminous pterocarpan biosynthesis is a dirigent domain-containing protein with isoflavanol dehydratase activity. Plant Cell Physiol 58 (2017) 398-408. [PMID: 28394400]