ID 1.1.1.328 DE nicotine blue oxidoreductase. CA (1) 3,3'-bipyridine-2,2',5,5',6,6'-hexol + NADP(+) = (E)- CA 2,2',5,5'-tetrahydroxy-6H,6'H-(3,3'-bipyridinylidene)-6,6'-dione + 3 H(+) CA + NADPH. CA (2) 3,3'-bipyridine-2,2',5,5',6,6'-hexol + NAD(+) = (E)- CA 2,2',5,5'-tetrahydroxy-6H,6'H-(3,3'-bipyridinylidene)-6,6'-dione + 3 H(+) CA + NADH. CC -!- The enzyme, characterized from the nicotine degrading bacterium CC Arthrobacter nicotinovorans, catalyzes the reduction of 'nicotine CC blue' to its hydroquinone form (the opposite direction from that CC shown). CC -!- Nicotine blue is the name given to the compound formed by the CC autocatalytic condensation of two molecules of 2,3,6- CC trihydroxypyridine, an intermediate in the nicotine degradation CC pathway. CC -!- The main role of the enzyme may be to prevent the intracellular CC formation of nicotine blue semiquinone radicals, which by redox CC cycling would lead to the formation of toxic reactive oxygen species. CC -!- The enzyme possesses a slight preference for NADH over NADPH. DR Q93NF6, NBOR_PAENI ; //