Involved in the degradation of L-nicotine (PubMed:5849820). Catalyzes the oxidation of (S)-6-hydroxynicotine (6-hydroxy-L-nicotine) to 6-hydroxypseudooxynicotine (PubMed:5849820, PubMed:4965794, PubMed:5646150, PubMed:21383134, PubMed:26744768, PubMed:28080034). Oxidation of the pyrrolidine ring of (S)-6-hydroxynicotine leads to the formation of the optically inactive 6-hydroxy-N-methylmyosmine, which hydrolyzes spontaneously to 6-hydroxypseudooxynicotine (PubMed:4965794, PubMed:21383134, PubMed:26744768, PubMed:28080034). Acts with absolute stereospecificity on the L-form of 6-hydroxynicotine (PubMed:4965794). Can also use (S)-6-hydroxynornicotine (PubMed:26744768, PubMed:28080034). (S)-6-hydroxynicotine + H2O + O2 = 6-hydroxypseudooxynicotine + H2O2 (S)-6-hydroxynicotine + O2 = 6-hydroxy-N-methylmyosmine + H2O2 Binds 1 FAD per subunit. Inhibited by (R)-6-hydroxynicotine (PubMed:5849820, PubMed:4965794). Inhibited by high concentrations of phenanthroline (PubMed:5646150). Activity is strongly affected by Hg(2+) and p-chloromercuriphenylsulfonate, but not by N-ethylmaleimide and 5,5'-dithiobis-(2-nitrobenzoate) (PubMed:5646150). kcat is 30 sec(-1) with (S)-6-hydroxynicotine as substrate. kcat is 16 sec(-1) with (S)-6-hydroxynornicotine as substrate. Fairly stable between pH 6 and 9. Alkaloid degradation; nicotine degradation; 6-hydroxypseudooxynicotine from nicotine (S-isomer route): step 2/2. Homodimer. Induced in the presence of L-nicotine and D-nicotine (PubMed:5849820). Expressed during logarithmic growth and stationary phase (PubMed:4019415). Consists of two domains, an FAD-binding domain and a substrate-binding domain (PubMed:20006620). The inactive D-stereoisomer binds in mirror symmetry with respect to the catalytic axis, revealing absolute stereospecificity of hydrogen transfer to the flavin (PubMed:21383134). Belongs to the flavin monoamine oxidase family.