数据之源，洞见之始

BioCyc:RXN-3481

Isoflavone O-methylation is a key reaction for the formation of pterocarpan phytoalexins such as medicarpin. Isoflavone specific O-methyltransferases have been purified expressing a high in vitro affinity for the methylation ofthe A-ring 7-hydroxyl group of daidzein.The resulting product, isoformononetin (7-O-methyldaidzein), is a rare naturally occurring compound which is unlikelyto be involved in the formation of medicarpin. No products of the 7-O-methylation of daidzein have been demonstratedto accumulate in elicited alfalfa cell cultures suggesting that this reaction may not occur in vivo.Recently, a daidzein-7-O-methyltransferase (D7OMT) has been purified from Glycyrrhiza echinata. |CITS: [12610212]|The distinct biochemistry of D7OMT and the distant phylogenetic relationship to another O-methyltransferase(2,7,4'-trihydroxyisoflavanone 4'-O-methyltransferase - HI4'OMT) acting specifically on 2,7,4'-trihydroxyisoflavanoneimplies a new scheme of formonetin biosynthesis which excludes the 4-O-methylation of daidzein.