131771-46-5Relevant articles and documents
Mass spectrometric studies of the path of carbon in photosynthesis: Positional isotopic analysis of 13C-labelled C4 to C7 sugar phosphates
MacLeod, John K.,Flanigan, Ian L.,Williams, John F.,Grant Collins
, p. 500 - 508 (2001)
The (EIMS) electron ionization mass spectrometric fragmentation patterns of the methoxime- and ethoximetrimethylsilyl (TMS) derivatives of C4 to C7 sugars involved as phosphates in the Calvin pathway of photosynthesis in plants were analysed by gas chromatography/EIMS using specifically labelled 13C analogs. In general, most but not all of the major ions in the mass spectra arise from single carbon-carbon bond cleavages of the straight-chain derivatives. The results confirm that GC/MS of the alkoxime-TMS derivatives is a viable method for measuring 163C incorporations at individual carbon atoms in each of the sugar phosphates during photosynthetic experiments with 13CO2. Copyright
Analysis of metabolic pathways via quantitative prediction of isotope labeling patterns: A retrobiosynthetic 13C NMR study on the monoterpene loganin
Eichinger, Dietmar,Bacher, Adelbert,Zenk, Meinhart H.,Eisenreich, Wolfgang
, p. 223 - 236 (2007/10/03)
The monoterpene loganin serves as a precursor in the biosynthetic pathways of numerous indole alkaloids. In contrast to earlier studies, we present evidence that the biosynthesis of loganin in Rauwolfia serpentina cells proceeds mainly via the deoxyxylulose pathway and not by the mevalonate pathway. This conclusion is based on experiments using a R. serpentina cell culture supplied with 13C-labeled samples of glucose, ribose/ribulose, pyruvate or glycerol. Loganin was isolated from biomass, and the hydrolysis of cellular protein afforded amino acids. The isolated metabolites were analyzed by NMR spectroscopy. The 13C-labeling patterns of isolated amino acids were then used to reconstruct the labeling patterns of phosphoenol pyruvate, pyruvate and acetyl CoA. These labeling patterns were subsequently used to predict labeling patterns for dimethylallyl pyrophosphate and isopentenyl pyrophosphate via the mevalonate and deoxyxylulose pathway, respectively. The observed labeling patterns of the terpenoid moieties in loganin were in excellent agreement with the deoxyxylulose prediction. The minor incorporation of mevalonate into loganin observed in earlier studies can be attributed to metabolite exchange between the two terpenoid pathways. The possibility of crosstalk between the two pathways in plants and plant cell cultures stresses the need for a quantitative analysis of general carbon metabolism in order to determine the partitioning between the mevalonate and deoxyxylulose pathway. The present study shows that a wide variety of general metabolic precursors can fulfill this task in conjunction with the retrobiosynthetic concept.
