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Site‐specific isotope fractionation of hydrogen in the biosynthesis of plant fatty acids
Author(s) -
QUEMERAIS B.,
MABON F.,
NAULET N.,
MARTIN G. J.
Publication year - 1995
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1995.tb00609.x
Subject(s) - fractionation , isotope fractionation , chemistry , isotope ratio mass spectrometry , deuterium , isotope , fatty acid , isotopic labeling , isotope analysis , mass spectrometry , chromatography , biochemistry , organic chemistry , biology , ecology , physics , quantum mechanics
The overall deuterium content of plant lipids has been investigated by isotope ratio mass spectrometry (IRMS), and the site‐specific natural isotope fractionation of hydrogen has been studied by 2 H‐NMR at natural abundance (SNIF‐NMR). An analytical strategy has been developed in order to exploit the isotopomeric composition determined in clusters associated with different chemical sites of one or several fatty acid components. The method, which combines spectrometric and chromatographic data, enables isotopic criteria to be directly derived from raw vegetable oils containing in general two saturated and two unsaturated fatty acids. These results provide new information on isotopic fractionation caused by biochemical, physiological and natural environmental effects. Some alternation in the molecular deuterium distribution has been detected which may be related to the mechanism of fatty acid elongation. The successive methylene groups introduced through malonyl CoA are the subjects of different kinetic isotope effects since one of them is exclusively derived from NADH whereas the other has a contribution from pyruvate. A discriminant analysis of the cluster isotopic parameters enables several kinds of botanical precursors to be distinguished. The authenticating performances can be improved by taking into account the influence of climatic effects related to the region in which the plant grew.