NMR-based fluxomics: Quantitative 2D NMR methods for isotopomers analysis

We have investigated the reliability of 2D-COSY and 2D-TOCSY experiments to provide accurate measurements of C-13-enrichments in complex mixtures of C-13-labelled metabolites. This was done from both theoretical considerations and experimental investigations. The results showed that 2D-TOCSY but not 2D-COSY could provide accurate measurements of C-13-enrichments, provided efficient zero-quantum filters were applied during the mixing period. This approach extends the range of NMR methods applicable in C-13-labelling experiments and is suitable to investigating the dynamic behaviour of metabolic systems. (C) 2007 Elsevier Ltd. All rights reserved.