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Title:The connectivity structure, giant strong component and centrality of metabolic networks
Authors: Hongwu Ma ; An-Ping Zeng
Date: 2003
Publication Title:Bioinformatics
Publisher:Oxford University Press
Publication Type:Journal Article Publication Status:Published
Volume No:19(11) Page Nos:1423-1430
DOI:10.1093/bioinformatics/btg177 ISBN/ISSN:1460-2059
Structural and functional analysis of genomebased large-scale metabolic networks is important for understanding the design principles and regulation of the metabolism at a system level. The metabolic network is conventionally considered to be highly integrated and very complex. A rational reduction of the metabolic network to its core structure and a deeper understanding of its functional modules are important. Results: In this work, we show that the metabolites in a metabolic network are far from fully connected. A connectivity structure consisting of four major subsets of metabolites and reactions, i.e. a fully connected sub-network, a substrate subset, a product subset and an isolated subset is found to exist in metabolic networks of 65 fully sequenced organisms. The largest fully connected part of a metabolic network, called the giant strong component (GSC) , represents the most complicated part and the core of the network and has the feature of scale-free networks. The average path length of the whole network is primarily determined by that of the GSC. For most of the organisms, GSC normally contains less than one-third of the nodes of the network. This connectivity structure is very similar to the bow-tie structure of World Wide Web. Our results indicate that the bow-tie structure may be common for largescale directed networks. More importantly, the uncovered structure feature makes a structural and functional analysis of large-scale metabolic network more amenable. As shown in this work, comparing the closeness centrality of the nodes in the GSC can identify the most central metabolites of a metabolic network. To quantitatively characterize the overall connection structure of the GSC we introduced the term overall closeness centralization index (OCCI) . OCCI correlates well with the average path length of the GSC and is a useful parameter for a system-level comparison of metabolic networks of different organisms.
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Bibtex format
author = { Hongwu Ma and An-Ping Zeng },
title = {The connectivity structure, giant strong component and centrality of metabolic networks},
journal = {Bioinformatics},
publisher = {Oxford University Press},
year = 2003,
volume = {19(11)},
pages = {1423-1430},
doi = {10.1093/bioinformatics/btg177},
url = {},

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