title: Farnesol and farnesal dehydrogenase(s) in corpora allata of the tobacco hornworm moth, Manduca sexta.
abstract: The metabolism of [3H]farnesol was studied in cell-free preparations of corpora allata from the tobacco hornworm, Manduca sexta, to assess the role of this presumed biosynthetic precursor of juvenile hormone (JH) III. A reversed-phase ion-pair liquid chromatographic (RP-IPC) procedure was devised to separate farnesol from several potential intermediates in its presumed metabolism to JH III: farnesal, farnesoic acid, 10,11-epoxyfarnesoic acid, and methyl farnesoate. Following incubation of (2E,6E)-[1,5,9-3H]farnesol with homogenates of corpora allata from fifth instar larvae or adult female M. sexta, and analysis by RP-IPC, the major radiolabeled products corresponded to farnesoic acid, farnesal, and a polar product(s) presumably derived from the tritium on C-1 of farnesol. Inclusion of NAD+ in the incubations conducted with crude homogenates resulted in enhanced [3H]farnesol metabolism, decreased accumulation of [3H]farnesal, and increased levels of [3H]farnesoic acid. Substitution of NADP+ for NAD+ was ineffective, suggesting that farnesol and/or farnesal dehydrogenase were NAD+-dependent enzymes. Pellet fractions obtained by differential centrifugation of crude homogenates exhibited both farnesol and farnesal dehydrogenase activity but only the latter was clearly stimulated by addition of NAD+. The alcohol/aldehyde dehydrogenase(s) showed some substrate specificity for the 2E isomer; nerol and (2Z,6E)-farnesol were barely metabolized under conditions in which either geraniol or (2E,6E)-farnesol were rapidly oxidized. The identity of the [3H]farnesal zone obtained from RP-IPC was further established by normal-phase liquid chromatography and by gas-liquid chromatography-mass spectrometry.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D000445:Aldehyde Oxidoreductases / Q000378:metabolism*; D000818:Animals; D005204:Farnesol / Q000378:metabolism*; D005260:Female; D007605:Juvenile Hormones / Q000096:biosynthesis; D007814:Larva / Q000378:metabolism; D007915:Lepidoptera / Q000378:metabolism*; D009036:Moths / Q000378:metabolism*; D064430:NAD (+) and NADP (+) Dependent Alcohol Oxidoreductases; D011106:Polyisoprenyl Phosphates / Q000378:metabolism; D012717:Sesquiterpenes; D014316:Tritium
chemical_list: D007605:Juvenile Hormones; D011106:Polyisoprenyl Phosphates; D012717:Sesquiterpenes; D014316:Tritium; D005204:Farnesol; C004808:farnesyl pyrophosphate; D000429:Alcohol Oxidoreductases; D064430:NAD (+) and NADP (+) Dependent Alcohol Oxidoreductases; C040714:farnesol dehydrogenase; D000445:Aldehyde Oxidoreductases; C040715:farnesal dehydrogenase