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A 13 C NMR spectrometric method for the determination of intramolecular δ 13 C values in fructose from plant sucrose samples
Author(s) -
Gilbert Alexis,
Silvestre Virginie,
Robins Richard J.,
Tcherkez Guillaume,
Remaud Gérald S.
Publication year - 2011
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2011.03690.x
Subject(s) - sucrose , chemistry , intramolecular force , derivatization , fructose , carbon 13 nmr , moiety , nuclear magnetic resonance spectroscopy , stereochemistry , organic chemistry , high performance liquid chromatography
Summary• Recent developments in 13 C NMR spectrometry have allowed the determination of intramolecular 13 C/ 12 C ratios with high precision. However, the analysis of carbohydrates requires their derivatization to constrain the anomeric carbon. Fructose has proved to be particularly problematic because of a byproduct occurring during derivatization and the complexity of the NMR spectrum of the derivative. • Here, we describe a method to determine the intramolecular 13 C/ 12 C ratios in fructose by 13 C NMR analysis of the acetyl‐isopropylidene derivative. • We have applied this method to measure the intramolecular 13 C/ 12 C distribution in the fructosyl moiety of sucrose and have compared this with that in the glucosyl moiety. Three prominent features stand out. First, in sucrose from both C 3 and C 4 plants, the C‐1 and C‐2 positions of the glucosyl and fructosyl moieties are markedly different. Second, these positions in C 3 and C 4 plants show a similar profile. Third, the glucosyl and fructosyl moieties of sucrose from Crassulacean acid metabolism (CAM) metabolism have a different profile. • These contrasting values can be interpreted as a result of the isotopic selectivity of enzymes that break or make covalent bonds in glucose metabolism, whereas the distinctive 13 C pattern in CAM sucrose probably indicates a substantial contribution of gluconeogenesis to glucose synthesis.