Covalently bound FAD in D-6-hydroxynicotine oxidase from Arthrobacter oxidans

In Arthrobacter oxidans, an enzymatically inactive protein which is in a close biosynthetic relationship to the active D-6-hydroxynicotine oxidase and may serve as a precursor for its formation was purified and shown to be homogeneous by gel electrophoresis. It consists of one polypeptide chain of about the same molecular weight (50 000 daltons) as the active enzyme. The purified protein lacks the absorption in the visible range characteristic of flavoproteins. Amino acid analysis and peptide mapping yielded similar results for both proteins. They also share the same C-terminal amino acids,-lysinetyrosine; the N-terminal residue is serine in the case of D-6-hydroxynicotine oxidase while that of the coinduced protein was found to be blocked.