title: Quantitative analysis of metabolic mixtures by two-dimensional 13C constant-time TOCSY NMR spectroscopy.
abstract: An increasing number of organisms can be fully (13)C-labeled, which has the advantage that their metabolomes can be studied by high-resolution two-dimensional (2D) NMR (13)C-(13)C constant-time (CT) total correlation spectroscopy (TOCSY) experiments. Individual metabolites can be identified via database searching or, in the case of novel compounds, through the reconstruction of their backbone-carbon topology. Determination of quantitative metabolite concentrations is another key task. Because strong peak overlaps in one-dimensional (1D) NMR spectra prevent straightforward quantification through 1D peak integrals, we demonstrate here the direct use of (13)C-(13)C CT-TOCSY spectra for metabolite quantification. This is accomplished through the quantum mechanical treatment of the TOCSY magnetization transfer at short and long-mixing times or by the use of analytical approximations, which are solely based on the knowledge of the carbon-backbone topologies. The methods are demonstrated for carbohydrate and amino acid mixtures.
authors.affiliation: Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306, USA.
authors.forename: Kerem
authors.initials: K
authors.lastname: Bingol
authors.forename: Fengli
authors.initials: F
authors.lastname: Zhang
authors.forename: Lei
authors.initials: L
authors.lastname: Bruschweiler-Li
authors.forename: Rafael
authors.initials: R
authors.lastname: Brüschweiler
mesh_terms: D002247:Carbon Isotopes; D045424:Complex Mixtures / Q000032:analysis* / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D055432:Metabolomics / Q000379:methods*
chemical_list: D002247:Carbon Isotopes; D045424:Complex Mixtures