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Allene oxide and aldehyde biosynthesis in starfish oocytes
A R Brash1, M A Hughes, D J Hawkins
1Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-6602.
The Journal of Biological Chemistry
|December 5, 1991
Summary
Starfish oocytes biosynthesize allene oxides, unusual epoxides, from arachidonic acid. This discovery marks the first identification of allene oxide synthase and hydroperoxide lyase enzymes in an animal cell.
Area of Science:
- Biochemistry
- Marine Biology
- Enzymology
Background:
- Allene oxides are unusual epoxides formed from fatty acid hydroperoxides.
- In plants, allene oxide synthesis is crucial for jasmonic acid production, a plant growth regulator.
Purpose of the Study:
- To investigate the biosynthesis of allene oxides in animal cells.
- To identify and characterize allene oxide synthase and hydroperoxide lyase activities in starfish oocytes.
Main Methods:
- High-pressure liquid chromatography (HPLC)
- UV spectroscopy
- Gas chromatography-mass spectrometry (GC-MS)
- Proton nuclear magnetic resonance (1H-NMR) spectroscopy
Main Results:
- Biosynthesis of allene oxide (8R)-8,9-epoxyeicosa-(5Z,9,11Z,14Z)-tetraenoic acid from arachidonic acid in starfish oocytes.
- Identification of alpha-ketol 8-hydroxy-9-ketoeicosa-(5Z,11Z,14Z)-trienoic acid as a major hydrolysis product.
- Detection of hydroperoxide lyase activity cleaving the substrate into C7 and C13 fragments, including (5Z)-7-hydroxyheptenoic acid and aldehydes.
Conclusions:
- This study provides the first definitive localization of allene oxide synthase and hydroperoxide lyase activities to an animal cell (starfish oocytes).
- These enzymes are involved in the metabolism of arachidonic acid in starfish.
- Lipoxygenase products may play distinct roles in starfish oocyte maturation and development.