JBC, Vol. 250, Issue 19, 7747-7751, Oct, 1975
Covalently bound FAD in d-6-hydroxynicotine oxidase. Immunological studies of D- and L-6-hydroxynicotine oxidase: evidence for a D-enzyme precursor
M. Bruhmuller, A. Schimz, L. Messmer and K. Decker
Antersera prepared against both enantiozymes, D- and L-6-hydroxynicotine
oxidase, formed precipitins in double diffusion tests with their respective
antigens only. A mixture of the two antisera caused spur formation of the
two precipitin lines obtained with the pure enzymes. Antiserum to
L-apoprotein reacted with native L-enzyme and L-apoprotein but not with the
D-sspecific enzyme. D-6-hydroxynicotine oxidase activity was inhibited by
the anti-D-antiserum, leaving the L-enzyme fully active, while
anti-L-antiserum inhibited the L- but not the D-specific activity. The
delayed induction of D-6-hydroxynicotine oxidase as compared to the other
activities of the nicotine-degrading sequence and the differential
immunochemical behavior of the enantiozymes allowed the search for a
D-enzyme precursor. In cells harvested 3 hours after the addition of
DL-nicotine, the L-enzyme activity was present, whereas no D-enzyme
activity could be detected. However, an extract of these cells did form an
immunoprecipitin line with anti-D-antiserum. L-6-Hydroxynicotine oxidase,
but no D-6-hydroxynicotine oxidase activity, could also be induced in
Arthrobacter oxidans grown in a medium with a high glucose content and
DL-nicotine as the sole nitrogen source. An extract of these L-induced
cells produced the specific immunoprecipitation with anti-D-antiserum. A
pulse-chase experiment with cells grown first on glucose and DL-nicotine in
the presence of [14C]leucine and then in an unlabeled medium which induces
D-6-hydroxynicotine oxidase activity resulted in a radioactive
D-enzyme-immunoprecipitin line. From these experiments it is concluded that
a precursor of the active D-enzyme is induced simultaneously with the other
nicotine-degrading enzymes.