S-(-)-nicotine-1'-N-oxide reductase activity of rat liver aldehyde oxidase.

In the present study, a rat liver cytosolic enzyme responsible for reduction of S-(-)-nicotine-1'-N-oxide to S-(-)-nicotine was investigated. We found that aldehyde oxidase (EC 1.2.3.1) can function as a S-(-)-nicotine-1'-N-oxide reductase in the presence of its electron donor such as 2-hydroxypyrimidine. The apparent K(m) and Vmax values of the enzyme for the N-oxide were 0.24 mM and 30.3 nmol/10 min/mg protein, respectively.