213825-57-1Relevant articles and documents
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.
Two-bond 13C-13C spin-coupling constants in carbohydrates: New measurements of coupling signs
Zhao, Shikai,Bondo, Gail,Zajicek, Jaroslav,Serianni, Anthony S.
, p. 145 - 152 (2007/10/03)
D-(1,3,6-13C3)Allose (1), (13C)methyl α-D-(1,2-13C2)glucopyranoside (2) and (13C)methyl β-D-(1,2-13C2)glucopyranoside (3) were synthesized and used to establish the signs of their constituent 2J(CCC) or 2J(COC) values (2J(C1,C3) in the α-pyranose of 1 (15), and 2J(C1,CH3) in 2 and 3). Compounds 2, 3 and 15 contain three mutually coupled labeled carbons, thus creating a three-spin system from which crosspeak displacements in 13C-13C COSY-45 spectra were used to determine coupling signs. In all compounds, at least one 3J(CC) value was present as an internal reference: 3J(C2,CH3 in 2 and 3, and 3J(C1,C6) and 3J(C3,C6) in 15. 2J(C1,CH3), in 2 and 3, and 2J(C1,C3) in 15, were found to be negative, thus providing experimental confirmation of the sign predictions made via the projection resultant rule described recently.