Abstract
In this paper the method of signal-flow graphs is used for calculating the Control Coefficients of metabolic pathways in terms of enzyme elasticities. The method is applied to an unbranched pathway (a) without feedback or feedforward regulation and (b) with feedback inhibition of the first enzyme by the last variable metabolite. It is shown that, by using a signal-flow graph, the control structure of a metabolic pathway can be represented in a graphical manner directly from the configuration of the pathway, without the necessity of writing the governing equations in a matrix form. From a signal-flow graph the various Control Coefficients can be evaluated in an easy and straightforward fashion without recourse to matrix inversion or other algebraic techniques. A signal-flow graph also provides a visual framework for analysing the cause-effect relationships of the individual enzymes.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Fell D. A., Sauro H. M. Metabolic control and its analysis. Additional relationships between elasticities and control coefficients. Eur J Biochem. 1985 May 2;148(3):555–561. doi: 10.1111/j.1432-1033.1985.tb08876.x. [DOI] [PubMed] [Google Scholar]
- Heinrich R., Rapoport T. A. A linear steady-state treatment of enzymatic chains. General properties, control and effector strength. Eur J Biochem. 1974 Feb 15;42(1):89–95. doi: 10.1111/j.1432-1033.1974.tb03318.x. [DOI] [PubMed] [Google Scholar]
- Hofmeyr J. H. Control-pattern analysis of metabolic pathways. Flux and concentration control in linear pathways. Eur J Biochem. 1989 Dec 8;186(1-2):343–354. doi: 10.1111/j.1432-1033.1989.tb15215.x. [DOI] [PubMed] [Google Scholar]
- Kacser H., Burns J. A. The control of flux. Symp Soc Exp Biol. 1973;27:65–104. [PubMed] [Google Scholar]
- Reder C. Metabolic control theory: a structural approach. J Theor Biol. 1988 Nov 21;135(2):175–201. doi: 10.1016/s0022-5193(88)80073-0. [DOI] [PubMed] [Google Scholar]
- Wanders R. J., Van Roermund C. W., Meijer A. J. Analysis of the control of citrulline synthesis in isolated rat-liver mitochondria. Eur J Biochem. 1984 Jul 16;142(2):247–254. doi: 10.1111/j.1432-1033.1984.tb08278.x. [DOI] [PubMed] [Google Scholar]