Metabolites 2014, 4(2), 408-420; doi:10.3390/metabo4020408
Article

Reliable Metabolic Flux Estimation in Escherichia coli Central Carbon Metabolism Using Intracellular Free Amino Acids

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Received: 17 March 2014; in revised form: 10 May 2014 / Accepted: 20 May 2014 / Published: 30 May 2014
(This article belongs to the Special Issue Metabolomics and Biotechnology)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: 13C metabolic flux analysis (MFA) is a tool of metabolic engineering for investigation of in vivo flux distribution. A direct 13C enrichment analysis of intracellular free amino acids (FAAs) is expected to reduce time for labeling experiments of the MFA. Measurable FAAs should, however, vary among the MFA experiments since the pool sizes of intracellular free metabolites depend on cellular metabolic conditions. In this study, minimal 13C enrichment data of FAAs was investigated to perform the FAAs-based MFA. An examination of a continuous culture of Escherichia coli using 13C-labeled glucose showed that the time required to reach an isotopically steady state for FAAs is rather faster than that for conventional method using proteinogenic amino acids (PAAs). Considering 95% confidence intervals, it was found that the metabolic flux distribution estimated using FAAs has a similar reliability to that of the PAAs-based method. The comparative analysis identified glutamate, aspartate, alanine and phenylalanine as the common amino acids observed in E. coli under different culture conditions. The results of MFA also demonstrated that the 13C enrichment data of the four amino acids is required for a reliable analysis of the flux distribution.
Keywords: metabolic flux analysis; intracellular free amino acids; Escherichia coli; GC-MS
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MDPI and ACS Style

Okahashi, N.; Kajihata, S.; Furusawa, C.; Shimizu, H. Reliable Metabolic Flux Estimation in Escherichia coli Central Carbon Metabolism Using Intracellular Free Amino Acids. Metabolites 2014, 4, 408-420.

AMA Style

Okahashi N, Kajihata S, Furusawa C, Shimizu H. Reliable Metabolic Flux Estimation in Escherichia coli Central Carbon Metabolism Using Intracellular Free Amino Acids. Metabolites. 2014; 4(2):408-420.

Chicago/Turabian Style

Okahashi, Nobuyuki; Kajihata, Shuichi; Furusawa, Chikara; Shimizu, Hiroshi. 2014. "Reliable Metabolic Flux Estimation in Escherichia coli Central Carbon Metabolism Using Intracellular Free Amino Acids." Metabolites 4, no. 2: 408-420.


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