title: Incorporation of atmospheric oxygen into the carbonyl functionality of the protochlorophyllide isocyclic ring.
abstract: Detached cucumber (Cucumis sativus L. var. Beit Alpha) cotyledons incubated in darkness with 5-aminolaevulinic acid and either 16O2 air (control) or 18O2 in N2 accumulated protochlorophyllide. This was converted into methyl phaeoporphyrin alpha 5 and analysed by mass spectrometry. The molecular ion of the methyl phaeoporphyrin alpha 5 derived from the 18O2 incubation was 2 mass units greater than that of the control, establishing that the oxo oxygen atom of the isocyclic ring is derived from atmospheric oxygen.
authors.affiliation: Department of Botany, University of California, Davis 95616.
authors.forename: C J
authors.initials: CJ
authors.lastname: Walker
authors.forename: K E
authors.initials: KE
authors.lastname: Mansfield
authors.forename: K M
authors.initials: KM
authors.lastname: Smith
authors.forename: P A
authors.initials: PA
authors.lastname: Castelfranco
mesh_terms: D001272:Atmosphere; D002734:Chlorophyll / Q000031:analogs & derivatives*; D013058:Mass Spectrometry; D010100:Oxygen / Q000378:metabolism*; D010944:Plants / Q000378:metabolism*; D011521:Protochlorophyllide / Q000031:analogs & derivatives / Q000378:metabolism*
chemical_list: D002734:Chlorophyll; D011521:Protochlorophyllide; C058793:methyl phaeoporphyrin a(5); D010100:Oxygen