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Open Access Open Badges Methodology article

Exhaustive identification of steady state cycles in large stoichiometric networks

Jeremiah Wright12 and Andreas Wagner1234*

Author Affiliations

1 Department of Biochemistry, University of Zurich, Zurich, Switzerland

2 Swiss Institute of Bioinformatics, Lausanne, Switzerland

3 Sante Fe Institute, Sante Fe, New Mexico, USA

4 Department of Biology, The University of New Mexico, Albuquerque, New Mexico, USA

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BMC Systems Biology 2008, 2:61  doi:10.1186/1752-0509-2-61

Published: 11 July 2008



Identifying cyclic pathways in chemical reaction networks is important, because such cycles may indicate in silico violation of energy conservation, or the existence of feedback in vivo. Unfortunately, our ability to identify cycles in stoichiometric networks, such as signal transduction and genome-scale metabolic networks, has been hampered by the computational complexity of the methods currently used.


We describe a new algorithm for the identification of cycles in stoichiometric networks, and we compare its performance to two others by exhaustively identifying the cycles contained in the genome-scale metabolic networks of H. pylori, M. barkeri, E. coli, and S. cerevisiae. Our algorithm can substantially decrease both the execution time and maximum memory usage in comparison to the two previous algorithms.


The algorithm we describe improves our ability to study large, real-world, biochemical reaction networks, although additional methodological improvements are desirable.