Bioreaction Network Topology and Metabolic Flux Ratio Analysis by Biosynthetic Fractional 13C Labeling and Two-Dimensional NMR Spectroscopy

Biosynthetically directed fractional C-13 labeling of the proteinogenic amino acids is achieved by feeding a mixture of uniformly C-13-labeled and unlabeled carbon source compounds into a bioreaction network. Analysis of the resulting labeling pattern enables both a comprehensive characterization of the network topology and the determination of metabolic flux ratios. Attractive features with regard to routine applications are (i) an inherently small demand for C-13-labeled source compounds and (ii) the high sensitivity of two-dimensional [C-13,H-1]-correlation nuclear magnetic resonance spectroscopy for analysis of C-13-labeling patterns. A user-friendly program, FCAL, is available to allow rapid data analysis. This novel approach, which recently also has been employed in conjunction with metabolic flux balancing to obtain reliable estimates of in vivo fluxes, enables efficient support of metabolic engineering and biotechnology process design. (C) 1999 Academic Press