A model of closely assembled consecutive enzymes on membranes: formation of hydroxycinnamic acids from L-phenylalanine on thylakoids of Dunaliella marina.
p-Hydroxycinnamic acid was found to be located within the plastids of the green alga Dunaliella marina. Thylakoid fractions desintegrated by ultrasonic treatment were capable of converting L-phenylalanine into o- and p-hydroxycinnamic acids; the hydroxylation reaction was increased by addition of NADPH. Hydroxycinnamic acids produced when [3-14C]cinnamate was incubated with varying amounts of [4'-3H]L-phenylalanine exhibited a 3H/14C ratio 10-150 times higher than that of the cinnamic acid reisolated from the incubation mixture. The lack of equilibration between cinnamate formed from L-phenylalanine and cinnamate added to the solution supports the hypothesis that cinnamate as an intermediate in hydroxycinnamate formation remains bound to the membrane enzyme complex. A model of membrane-bound multienzyme complexes is proposed for the conversion of aromatic amino acids into phenols.
D000460:Chlorophyta / Q000378:metabolism* / Q000648:ultrastructure; D002934:Cinnamates / Q000096:biosynthesis*; D003374:Coumarins / Q000032:analysis; D008566:Membranes / Q000032:analysis / Q000201:enzymology / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000378:metabolism; D008954:Models, Biological; D010649:Phenylalanine / Q000378:metabolism*; D010650:Phenylalanine Ammonia-Lyase / Q000378:metabolism
D002934:Cinnamates; D003374:Coumarins; D010649:Phenylalanine; D006899:Mixed Function Oxygenases; D010650:Phenylalanine Ammonia-Lyase