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Báo cáo Y học: C-labelling experiments

Modelling of the fluxes in central metabolism can be performed by combining labelling experiments with metabolite balancing. Using this approach, multiple samples from a cultivation of Saccharomyces cerevisiae in metabolic and isotopic steady state were analysed, and the metabolic fluxes in central metabolism were estimated. In the various samples, the estimates of the central metabolic pathways, the tricarboxylic acid cycle, the oxidative pentose phosphate pathway and the anaplerotic pathway, showed an unprecedented reproducibility | Eur. J. Biochem. 269 2795-2800 2002 FEBS 2002 doi 10.1046 j.1432-1033.2002.02959.x Analysis of flux estimates based on 13C-labelling experiments Bjarke Christensen Andreas Karoly Gombertt and Jens Nielsen Center for Process Biotechnology BioCentrum DTU Technical University of Denmark DK-2800 kg. Lyngby Denmark Modelling of the fluxes in central metabolism can be performed by combining labelling experiments with metabolite balancing. Using this approach multiple samples from a cultivation of Saccharomyces cerevisiae in metabolic and isotopic steady state were analysed and the metabolic fluxes in central metabolism were estimated. In the various samples the estimates of the central metabolic pathways the tricarboxylic acid cycle the oxidative pentose phosphate pathway and the anaplerotic pathway showed an unprecedented reproducibility. The high reproducibility was obtained with fractional labellings of individual carbon atoms as the calculational base illustrating that the more complex modelling using isotopomers is not necessarily superior with respect to reproducibility of the flux estimates. Based on these results some general difficulties in flux estimation are discussed. Keywords metabolic network analysis GC-MS labelling experiments pentose phosphate pathway. Methods for quantifying intracellular fluxes are important for understanding the interactions of the pathways in metabolic networks and such methods are therefore essential for the metabolic engineering approach to redirecting the metabolism towards production of desired metabolites. Flux estimation methods may be based on metabolite balances over intracellular metabolites labelling experiments or a combination of metabolite balances and labelling experiments. Thus much information has been obtained from metabolite balances which have been used to study carbon flux distribution redox metabolism and energetics of cellular metabolism 1 . This method is mathematically attractive as the equation system arising