Fig. 1.

Phenylalanine recruited into a diverse network of metabolism including the production of isoflavones and other specialized metabolites. Competition for the common substrate naringenin is highlighted, with downstream metabolites in yellow. Chalcone synthase (CHS) produces the chalcone, naringenin chalcone, and in legumes CHS coactively with chalcone reductase (CHR) forms isoliquiritigenin chalcone. Chalcone isomerase (CHI) converts the two chalcones to their flavanone derivatives: liquiritigenin and naringenin; the latter, as stated above, can be utilized by isoflavones synthase (IFS) or a whole host of other enzymes, to produce a variety of metabolites including the isoflavones. The multiple arrows indicate two or more steps in the pathway. Other enzymes labeled: PAL, phenylalanine ammonia lyase; C4H, cinnamate 4-hydroxylase; 4CL, 4-coumarate:CoA ligase; 2HID, 2-Hydroxyisoflavanone dehydratase; IOMT, isoflavone O-methyltransferase; F6H, flavonoid 6-hydroxylase