Customized Metabolomics Database for the Analysis of NMR 1H-1H TOCSY and 13C-1H HSQC-TOCSY Spectra of Complex Mixtures

A customized metabolomics NMR database, termed H-1(C-13)-TOCCATA, is introduced, which contains complete H-1 and C-13 chemical shift information on individual spin systems and isomeric states of common metabolites. Since this information directly corresponds to cross sections of 2D H-1-H-1 TOCSY and 2D C-13-H-1 HSQC-TOCSY spectra, it allows the straightforward and unambiguous identification of metabolites of complex metabolic mixtures at C-13 natural abundance from these types of experiments. The H-1(C-13)TOCCATA database, which is complementary to the previously introduced TOCCATA database for the analysis of uniformly C-13-labeled compounds, currently contains 455 metabolites, and it can be used through a publicly accessible web portal. We demonstrate its performance by applying it to 2D H-1-H-1 TOCSY and 2D C-13-H-1 HSQC-TOCSY spectra of a cell lysate from E. coli, which yields a substantial improvement over other databases, as well as ID NMR-based approaches, in the number of compounds that can be correctly identified with high confidence.