Reaction: 3,3'-bipyridine-2,2',5,5',6,6'-hexol + NAD(P)+ = (E)-2,2',5,5'-tetrahydroxy-6H,6'H-[3,3'-bipyridinylidene]-6,6'-dione + NAD(P)H + H+
For diagram of reaction click here.
Glossary: 3,3'-bipyridine-2,2',5,5',6,6'-hexol = nicotine blue leuco form
(E)-2,2',5,5'-tetrahydroxy-6H,6'H-[3,3'-bipyridinylidene]-6,6'-dione = nicotine blue
Other name(s): nboR (gene name)
Systematic name: 3,3'-bipyridine-2,2',5,5',6,6'-hexol:NADP+ 11-oxidoreductase
Comments: The enzyme, characterized from the nicotine degrading bacterium Arthrobacter nicotinovorans, catalyses the reduction of "nicotine blue" to its hydroquinone form (the opposite direction from that shown). Nicotine blue is the name given to the compound formed by the autocatalytic condensation of two molecules of 2,3,6-trihydroxypyridine, an intermediate in the nicotine degradation pathway. The main role of the enzyme may be to prevent the intracellular formation of nicotine blue semiquinone radicals, which by redox cycling would lead to the formation of toxic reactive oxygen species. The enzyme possesses a slight preference for NADH over NADPH.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:
1. Mihasan, M., Chiribau, C.B., Friedrich, T., Artenie, V. and Brandsch, R. An NAD(P)H-nicotine blue oxidoreductase is part of the nicotine regulon and may protect Arthrobacter nicotinovorans from oxidative stress during nicotine catabolism. Appl. Environ. Microbiol. 73 (2007) 2479-2485. [PMID: 17293530]