title: The measurement of the main PGE metabolite, 13,14-dihydro-15-keto prostaglandin E by radioimmunoassay using methyl oxime stabilization.
abstract: The measurement of 13,14-dihydro-15-keto prostaglandin E2 [PGEM] is complicated by the artefactual formation of compounds of the corresponding A series which are reactive towards protein. Existing methods of assay depend on the deliberate dehydration to the 'A' form followed by cyclization in alkaline solution to a bicyclic derivative which is stable and can be measured by radioimmunoassay. We report an alternative approach using methyl oximation of the 9- and 15-keto groups which confer stability on the molecule. This derivatization is simple and does not involve an active intermediate such as those of the PGA series. The antiserum for radioimmunoassay is raised against the methyl oxime form. The label is the methyl oxime of PGEM coupled to a tripeptide Pro-gly-tyr through the nitrogen in the proline ring. This is a linkage distinct from that used to raise the antiserum and thus is not preferentially recognized over the endogenous analyte; this results in a high sensitivity assay. The results correlated well with those from the bicyclic assay when both assays were used to measure the same samples of peripheral blood from women receiving a sustained release PGE pessary for ripening the cervix. The technique provides a rapid and reliable method for determining prostaglandin E metabolites.
authors.affiliation: Medical Research Council Reproductive Biology Unit, Edinburgh, UK.
authors.forename: R W
authors.initials: RW
authors.lastname: Kelly
authors.forename: A F
authors.initials: AF
authors.lastname: Gallacher
authors.forename: T A
authors.initials: TA
authors.lastname: Johnston
authors.forename: N W
authors.initials: NW
authors.lastname: Harrison
mesh_terms: D000527:Alprostadil / Q000031:analogs & derivatives* / Q000097:blood; D000595:Amino Acid Sequence; D000818:Animals; D003429:Cross Reactions; D005260:Female; D006801:Humans; D006898:Hydroxylamines; D008969:Molecular Sequence Data; D010091:Oximes; D011247:Pregnancy; D011817:Rabbits; D011863:Radioimmunoassay / Q000379:methods
chemical_list: D006898:Hydroxylamines; D010091:Oximes; C036808:13,14-dihydro-15-ketoprostaglandin E1; D000527:Alprostadil