Chlorophyll b to Chlorophyll a Conversion Precedes Chlorophyll Degradation in Hordeum vulgare L.

This study reveals by in vivodeuterium 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 % 2H)...

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Bibliographic Details
Published in:The Journal of biological chemistry 1999-07, Vol.274 (31), p.21811-21816
Main Authors: Folly, Patrick, Engel, Norbert
Format: Article
Language:English
Subjects:
chemical structure
chlorophyll
Chlorophyll - chemistry
Chlorophyll - metabolism
Chlorophyll A
dark
Darkness
degradation
Deuterium Oxide
Hordeum - metabolism
Hordeum vulgare
Kinetics
Magnetic Resonance Spectroscopy
metabolism
Models, Molecular
Molecular Structure
nuclear magnetic resonance spectroscopy
Plant Leaves - metabolism
reduction
spectral analysis
Spectrometry, Mass, Secondary Ion
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Summary:This study reveals by in vivodeuterium 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 % 2H). The resulting Chla 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 1H-, 2H-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 Chla 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.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.274.31.21811