  Graph theory and graph mining constitute rich fields of computational
techniques to study the structures, topologies and properties of graphs. These
techniques constitute a good asset in bioinformatics if there exist efficient
methods for transforming biological data into graphs. In this paper, we present
Protein Graph Repository (PGR), a novel database of protein 3D-structures
transformed into graphs allowing the use of the large repertoire of graph
theory techniques in protein mining. This repository contains graph
representations of all currently known protein 3D-structures described in the
Protein Data Bank (PDB). PGR also provides an efficient online converter of
protein 3D-structures into graphs, biological and graph-based description,
pre-computed protein graph attributes and statistics, visualization of each
protein graph, as well as graph-based protein similarity search tool. Such
repository presents an enrichment of existing online databases that will help
bridging the gap between graph mining and protein structure analysis. PGR data
and features are unique and not included in any other protein database. The
repository is available at http://wjdi.bioinfo.uqam.ca/.
