Fundamental Bioengineering

4Primary Metabolic Pathways and Metabolic Flux Analysis

John Villadsen

Summary

The objective of this chapter is to introduce the reader to metabolic flux analysis (MFA) – or more precisely to stoichiometry-based MFA. The first six sections of this chapter introduce the catabolic pathways in which free energy is produced to drive the cell-building anabolic pathways. An overview of these, so-called primary pathways will provide the reader who is primarily trained in the engineering sciences with at least a preliminary introduction to biochemistry and will also show how carbon is drained off the catabolic pathways to provide precursors for cell mass building and sometimes for important industrial products. Chapters 4.7 to 4.9 describe the quantitative basis for MFA. To analyze the flow of carbon in the metabolic network of cells is today a key discipline of bioengineering. Computer-based software for this purpose is freely available, and it is based on the theory of Chapters 4.8 and 4.9. In Chapter 5, this theory is extended to calculate the flow of labeled substrate in the network, and with the algorithms discussed in Chapter 5 a comprehensive analysis of the flow through complex networks is possible. As an introduction to MFA in “real” systems, the methods of Chapter 3 will, however, in Chapter 4.7 be treated systematically by the so-called substrate-to-product MFA technique. It is hoped that this “soft” introduction to a complex, but important discipline of bioengineering will ...