Reaction: S-adenosyl-L-methionine + 2,4',7-trihydroxyisoflavanone = S-adenosyl-L-homocysteine + 2,7-dihydroxy-4'-methoxyisoflavanone
For diagram of reaction click here.
Other name(s): SAM:2,4',7-trihydroxyisoflavanone 4'-O-methyltransferase; HI4'OMT; HMM1; MtIOMT5
Systematic name: S-adenosyl-L-methionine:2,7,4'-trihydroxyisoflavanone 4'-O-methyltransferase
Comments: Specifically methylates 2,4',7-trihydroxyisoflavanone on the 4'-position. No activity with isoflavones . The enzyme is involved in formononetin biosynthesis in legumes . The protein from pea (Pisum sativum) also methylates (+)-6a-hydroxymaackiain at the 3-position (cf. EC 18.104.22.1680, (+)-6a-hydroxymaackiain 3-O-methyltransferase) .
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:
1. Akashi, T., Sawada, Y., Shimada, N., Sakurai, N., Aoki, T. and Ayabe, S. cDNA cloning and biochemical characterization of S-adenosyl-L-methionine: 2,7,4'-trihydroxyisoflavanone 4'-O-methyltransferase, a critical enzyme of the legume isoflavonoid phytoalexin pathway. Plant Cell Physiol. 44 (2003) 103-112. [PMID: 12610212]
2. Deavours, B.E., Liu, C.J., Naoumkina, M.A., Tang, Y., Farag, M.A., Sumner, L.W., Noel, J.P. and Dixon, R.A. Functional analysis of members of the isoflavone and isoflavanone O-methyltransferase enzyme families from the model legume Medicago truncatula. Plant Mol. Biol. 62 (2006) 715-733. [PMID: 17001495]
3. Liu, C.J., Deavours, B.E., Richard, S.B., Ferrer, J.L., Blount, J.W., Huhman, D., Dixon, R.A. and Noel, J.P. Structural basis for dual functionality of isoflavonoid O-methyltransferases in the evolution of plant defense responses. Plant Cell 18 (2006) 3656-3669. [PMID: 17172354]
4. Akashi, T., VanEtten, H.D., Sawada, Y., Wasmann, C.C., Uchiyama, H. and Ayabe, S. Catalytic specificity of pea O-methyltransferases suggests gene duplication for (+)-pisatin biosynthesis. Phytochemistry 67 (2006) 2525-2530. [PMID: 17067644]