Enzymic synthesis of isoflavones.
The NADPH and oxygen-dependent conversion of (2S)-naringenin to genistein catalyzed by a microsomal preparation from elicitor-treated soybean cell suspension cultures has been resolved into two steps. In the first step (2S)-naringenin is converted to a product (P-2) which yields genistein in a second step. The chemical behaviour of P-2 and its ultraviolet and mass spectral data are consistent with a 2-hydroxyisoflavanone structure. The conversion of (2S)-naringenin to P-2 requires NADPH, oxygen and cytochrome P-450. The participation of cytochrome P-450 was demonstrated by CO inhibition of the reaction and its partial reversal by light, and by inhibition with typical cytochrome P-450 inhibitors. On a Percoll gradient the membrane fraction which catalyzes P-2 formation coincides with marker enzymes for the endoplasmic reticulum and with the position of cytochrome P-450. Enzymatic activity for conversion of P-2 to genistein is mainly present in the supernatant of the 160 000 X g fraction. This reaction, formally a dehydration, does not require NADPH or oxygen.
D002478:Cells, Cultured; D003577:Cytochrome P-450 Enzyme System / Q000502:physiology; D044950:Flavanones; D005419:Flavonoids / Q000096:biosynthesis* / Q000378:metabolism; D019833:Genistein; D006863:Hydrogen-Ion Concentration; D007529:Isoflavones / Q000096:biosynthesis*; D008623:Mercaptoethanol / Q000494:pharmacology; D008861:Microsomes / Q000378:metabolism; D009249:NADP / Q000494:pharmacology; D010100:Oxygen / Q000494:pharmacology; D013025:Glycine max; D013379:Substrate Specificity
D044950:Flavanones; D005419:Flavonoids; D007529:Isoflavones; D009249:NADP; D008623:Mercaptoethanol; D003577:Cytochrome P-450 Enzyme System; D019833:Genistein; C005273:naringenin; D010100:Oxygen