Molecular cloning and functional expression of codeinone reductase: the penultimate enzyme in morphine biosynthesis in the opium poppy Papaver somniferum.
Also acts on some other alkaloids, including codeine, normorphine and ethylmorphine, but only very slowly on 7,8-saturated derivatives such as dihydromorphine and dihydrocodeine. In the reverse direction, also reduces naloxone to the 6alpha-hydroxy analogue. Activated by 2-sulfanylethan-1-ol (2-mercaptoethanol).
Enzymatic reactions [BR:br08201]
1. Oxidoreductase reactions
1.1 Acting on the CH-OH group of donors
1.1.1 With NAD+ or NADP+ as acceptor
1.1.1.218
R03591 Morphine + NAD+ <=> Morphinone + NADH + H+