Claus Schneider
Last active: 4/5/2016

Synthesis and applications of stereospecifically (3)H-labeled arachidonic acids as mechanistic probes for lipoxygenase and cyclooxygenase catalysis.

Schneider C, Boeglin WE, Lai S, Cha JK, Brash AR
Anal Biochem. 2000 284 (1): 125-35

PMID: 10933865 · DOI:10.1006/abio.2000.4670

Stereospecifically (3)H-labeled substrates are useful tools in studying the mechanism of hydrogen abstractions involved in the oxygenation of polyunsaturated fatty acids. Here, we describe modified methods for the synthesis of arachidonic acids labeled with a single chiral tritium on the methylene groups at carbons 10 or 13. The appropriate starting material is a ketooctadecanoic acid which is prepared from an unsaturated C18 fatty acid precursor or by total synthesis. The (3)H label is introduced by NaB(3)H(4) reduction and the resulting tritiated hydroxy fatty acid then is tosylated, separated into the enantiomers by chiral phase HPLC, and subsequently transformed into stearic acids. A variety of stereospecifically labeled unsaturated fatty acids are obtained using literature methods of microbial transformation with the fungus Saprolegnia parasitica. Two applications are described: (i) In incubations of [10S-(3)H]- and [10R-(3)H]arachidonic acids in human psoriatic scales we show that a 12R-lipoxygenase accounts not only for synthesis of the major product 12R-HETE, but it contributes also, through subsequent isomerization, to the minor amounts of 12S-HETE. (ii) The [10R-(3)H]- and [10S-(3)H]arachidonic acids were also used to demonstrate that prostaglandin ring formation by cyclooxygenases does not involve carbocation formation at C-10 of arachidonic acid as was hypothesized recently.

Copyright 2000 Academic Press.

MeSH Terms (18)

Animals Arachidonic Acids Carbon Chromatography, High Pressure Liquid Cyclooxygenase 2 Dinoprostone Humans Hydrogen Hydroxyeicosatetraenoic Acids Isoenzymes Lipoxygenase Membrane Proteins Mice Models, Chemical Prostaglandin-Endoperoxide Synthases Psoriasis Stereoisomerism Time Factors

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