Numerical recipes in C (2nd ed.): the art of scientific computing
Numerical recipes in C (2nd ed.): the art of scientific computing
Handbook of Chemometrics and Qualimetrics: Part A
Handbook of Chemometrics and Qualimetrics: Part A
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The potential of using sole respirometric CO"2 labeling measurement for ^1^3C metabolic flux analysis was investigated by metabolic simulations. For this purpose a model was created, considering all CO"2 forming and consuming reactions in the central catabolic and anabolic pathways. To facilitate the interpretation of the simulation results, the underlying metabolic network was parameterized by physiologically meaningful flux parameters such as flux partitioning ratios at metabolic branch points and reaction reversibilities. For real case flux scenarios of the industrial amino acid producer Corynebacterium glutamicum and different commercially available ^1^3C-labeled tracer substrates, observability and output sensitivity towards key flux parameters was investigated. Metabolic net fluxes in the central metabolism, involving, e.g. glycolysis, pentose phosphate pathway, tricarboxylic acid cycle, anaplerotic carboxylation, and glyoxylate pathway were found to be determinable by the respirometric approach using a combination of [1-^1^3C] and [6-^1^3C] glucose in two parallel studies. The reversibilities of bidirectional reactions influence the isotopic labeling of CO"2 only to a negligible degree. On one hand, they therefore cannot be determined. On the other hand, their precise values are not required for the quantification of net fluxes. Computer-aided optimal experimental design was carried out to predict the quality of the information from the respirometric tracer experiments and identify suitable tracer substrates. A combination of [1-^1^3C] and [6-^1^3C] glucose in two parallel studies was found to yield a similar quality of information as compared to an approach with mass spectrometric labeling analysis of secreted products. The quality of information can be further increased by additional studies with [1,2-^1^3C"2] or [1,6-^1^3C"2] glucose. Respirometric tracer studies with sole labeling analysis of CO"2 are therefore promising for ^1^3C metabolic flux analysis. for ^1^3C metabolic flux analysis.