||A P-450 (heme-thiolate) cytochrome. The enzyme from Papaver rhoeas (field poppy) is specific for (S)-reticuline and does not act on the (R)-form. The enzyme from Papaver somniferum (opium poppy), which is involved in the biosynthesis of morphine and related alkaloids, forms a fusion protein with EC 18.104.22.168, 1,2-dehydroreticulinium reductase (NADPH), which catalyses the reduction of 1,2-dehydroreticuline to (R)-reticuline, thus forming an epimerase system that converts (S)-reticuline to (R)-reticuline.
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