Detecting and dissecting metabolic fluxes using biosynthetic fractional ¹³C labeling and two-dimensional NMR spectroscopy

The combined use of two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy and biosynthetic fractional ¹³C labeling of proteinogenic amino acids represents a novel approach for monitoring the response of metabolic fluxes to genetic manipulations or to variations of bioprocess parameters. Non-random ¹³-C-labeling patterns arising from incorporation of intact two- or three-carbon fragments from uniformly ¹³C-labeled source molecules into the amino acids are identified by 2D NMR, and are quantitatively related to the steady-state carbon fluxes from the source molecules to the final product. The relatively low cost of isotopes, and limited requirements for manpower and NMR instrument time make this approach of practical use for optimizing bioprocess parameters.