Metabolism of monoterpenes: oxidation of isopiperitenol to isopiperitenone, and subsequent isomerization to piperitenone by soluble enzyme preparations from peppermint (Mentha piperita) leaves
Soluble enzyme extracts from peppermint leaves, when treated with polystyrene resin to remove endogenous monoterpenes and assayed with unlabeled substrates coupled with capillary gas-liquid chromatographic/mass spectrometric detection methods, were shown to oxidize isopiperitenol to isopiperitenone, and to isomerize isopiperitenone to piperitenone. The enzymes responsible for the monoterpenol dehydrogenation and the subsequent allylic isomerization were separated and partially purified by chromatography on Sephadex G-150, and were shown to have molecular weights of approximately 66,000 and 54,000, respectively. The general properties of the NAD-dependent dehydrogenase were examined, and specificity studies indicated that a double bond adjacent to the carbinol carbon was a required structural feature of the monoterpenol substrate. General properties of the isomerase were also determined, and it was demonstrated that the double bond migration catalyzed by this enzyme involved an intramolecular 1,3-hydrogen transfer. These enzymatic transformations represent two key steps in the metabolic pathway for the conversion of the initially formed cyclic olefin, (+/-)-limonene, to (-)-menthol and related monoterpenes characteristic of peppermint. Some stereochemical features of these reactions, and of the overall biogenetic scheme, are described. 39 references, 5 figures.
- Research Organization:
- Washington State Univ., Pullman
- DOE Contract Number:
- AM06-76RL02221; AT06-82ER12027
- OSTI ID:
- 6258668
- Journal Information:
- Arch. Biochem. Biophys.; (United States), Journal Name: Arch. Biochem. Biophys.; (United States) Vol. 238:1; ISSN ABBIA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
BIOLOGICAL PATHWAYS
CHROMATOGRAPHY
COENZYMES
DATA
ENZYME ACTIVITY
ENZYMES
EXPERIMENTAL DATA
INFORMATION
LEAVES
LIQUID COLUMN CHROMATOGRAPHY
MASS SPECTROSCOPY
METABOLISM
MOLECULAR WEIGHT
NAD
NUCLEOTIDES
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PLANTS
PURIFICATION
SEPARATION PROCESSES
SPECTROSCOPY
TERPENES