Folly P Engel N 1999 This study reveals by in vivo deuterium labeling that in higher plants chlorophyll (Chl) b is converted to Chl a before degradation. For this purpose, de-greening of excised green primary leaves of barley (Hordeum vulgare) was induced by permanent darkness in the presence of heavy water (80 atom % (2)H). The resulting Chl a catabolite in the plant extract was subjected to chemical degradation by chromic acid. 3-(2-Hydroxyethyl)-4-methyl-maleimide, the key fragment that originates from the Chl catabolite, was isolated. High resolution (1)H-, (2)H-NMR and mass spectroscopy unequivocally demonstrates that a fraction of this maleimide fragment consists of a mono-deuterated methyl group. These results suggest that Chl b is converted into Chl a before degradation. Quantification proves that the initial ratio of Chl a:Chl b in the green plant is preserved to about 60-70% in the catabolite composition isolated from yellowing leaves. The incorporation of only one deuterium atom indicates the involvement of two distinguishable redox enzymes during the conversion. application/pdf https://sonar.ch/global/documents/283145 eng info:eu-repo/semantics/altIdentifier/doi/10.1074/jbc.274.31.21811 info:eu-repo/semantics/altIdentifier/pmid/10419497 info:eu-repo/semantics/openAccess The Journal of biological chemistry. - 1999 Chlorophyll Chlorophyll A Darkness Deuterium Oxide Hordeum Kinetics Magnetic Resonance Spectroscopy Models, Molecular Molecular Structure Plant Leaves Spectrometry, Mass, Secondary Ion Chlorophyll b to chlorophyll a conversion precedes chlorophyll degradation in Hordeum vulgare L. http://purl.org/coar/resource_type/c_6501