The Bacterial Oxidation of Nicotine

The synthesis of 2,3,6-trihydroxypyridine is described. The O2 labile product of the 2,6-dihydroxypyridine oxidasecatalyzed oxidation of 2,6-dihydroxypyridine was accumulated by making O2 concentration rate-limiting in the reaction. Under these conditions a precursor-product relation was shown for the enzyme product and nicotine blue pigment. The product of the enzyme reaction was degraded by cleavage enzyme derived from nicotine-grown cells, but not by crude extracts from noninduced cells. The ultraviolet spectrum of the product of the enzyme reaction, determined in the reaction mixture, is very similar to that of synthetic 2,3,6-trihydroxypyridine in the corresponding buffer. Both the enzymatic product and the synthetic product are substrates for the cleavage enzyme; the 4-methyl- and 4,5-dimethyl-substituted trihydroxypyridines are not. These data and the stoichiometry of the reaction suggest that the product of the oxidase reaction is 2,3,6-trihydroxypyridine.