title: Combinatorial complexity of pathway analysis in metabolic networks.
abstract: Elementary flux mode analysis is a promising approach for a pathway-oriented perspective of metabolic networks. However, in larger networks it is hampered by the combinatorial explosion of possible routes. In this work we give some estimations on the combinatorial complexity including theoretical upper bounds for the number of elementary flux modes in a network of a given size. In a case study, we computed the elementary modes in the central metabolism of Escherichia coli while utilizing four different substrates. Interestingly, although the number of modes occurring in this complex network can exceed half a million, it is still far below the upper bound. Hence, to a certain extent, pathway analysis of central catabolism is feasible to assess network properties such as flexibility and functionality.
authors.affiliation: Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany. klamt@mpi-magdeburg.mpg.de
authors.forename: Steffen
authors.initials: S
authors.lastname: Klamt
authors.forename: Jörg
authors.initials: J
authors.lastname: Stelling
mesh_terms: D003198:Computer Simulation; D004798:Enzymes / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism; D008433:Mathematics; D008954:Models, Biological; D015999:Multivariate Analysis
chemical_list: D004798:Enzymes; D029968:Escherichia coli Proteins