The PTGL web server provides a database of protein secondary structure topologies [Schäfer et al., 2015, Bioinformatics; May et al., 2010, Nucleic Acids Res.; May et al., 2004, Bioinformatics]. It is based on protein-ligand graphs computed by the VPLG software. The PTGL uses a graph-based model to describe the structure of proteins on the super-secondary structure level.
PTGL stands for Protein Topology Graph Library. It is a database of protein structure topologies modeled as undirected, labeled graphs. It provides a web server to visualize and analyze protein structure topologies at different scales, e.g., secondary structure level and chain level. The graph computation was done by our software Visualization of Protein-Ligand Graphs (VPLG). VPLG is based on the 3D atomic coordinates from the PDB either as legacy PDB file or as macromolecular Crystallographic Information File (mmCIF). Reading mmCIFs allows processing large protein structures (> 62 chains or > 99,999 atoms). The secondary structure assignment is parsed with small adaptions from a DSSP file.
Read more about PTGL...You can find worked out step-by-step examples with screenshots of the output of the following topics: