title: The role and source of 5'-deoxyadenosyl radical in a carbon skeleton rearrangement catalyzed by a plant enzyme.
abstract: The last step in the biosynthesis of tropane alkaloids is the carbon skeleton rearrangement of littorine to hyoscyamine. The reaction is catalyzed by a cell-free extract prepared from cultured hairy roots of Datura stramonium. Adenosylmethionine stimulated the rearrangement 10-20-fold and showed saturation kinetics with an apparent Km of 25 microM. It is proposed that S-adenosylmethionine is the source of a 5'-deoxyadenosyl radical which initiates the rearrangement in a similar manner as it does in analogous rearrangements catalyzed by coenzyme B12-dependent enzymes. Possible roles of S-adenosylmethionine as a radical source in higher plants are discussed.
authors.affiliation: Lehrstuhl für Biochemie, Institut für Organische Chemie, Universität Karlsruhe, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Ollagnier
authors.forename: E
authors.initials: E
authors.lastname: Kervio
authors.forename: J
authors.initials: J
authors.lastname: Rétey
mesh_terms: D001285:Atropine / Q000096:biosynthesis; D001286:Atropine Derivatives / Q000737:chemistry; D002384:Catalysis; D013286:Datura stramonium / Q000201:enzymology*; D003839:Deoxyadenosines / Q000737:chemistry* / Q000378:metabolism*; D004789:Enzyme Activation; D005609:Free Radicals / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000201:enzymology; D010946:Plants, Medicinal; D010947:Plants, Toxic; D012436:S-Adenosylmethionine / Q000737:chemistry / Q000378:metabolism; D014316:Tritium; D014326:Tropanes / Q000737:chemistry
chemical_list: D001286:Atropine Derivatives; D003839:Deoxyadenosines; D005609:Free Radicals; D010940:Plant Proteins; D014326:Tropanes; D014316:Tritium; C063158:littorine; C033714:5'-deoxyadenosine; D001285:Atropine; D012436:S-Adenosylmethionine