Databases protein binders

It is important to emphasize that this lattice database is highly idealized compared to real databases. Unlike the lattice database, real databases cannot be treated as thermodynamic ensembles of protein-ligand complexes equilibrated at room temperature [33,34]. Two of the more straightforward reasons are mentioned here. First, real databases are inherently biased toward strong binders (K < 10 pM), because weak binders are difficult to crystallize and of lesser interest. Second, as mentioned above, real databases are not composed of a representative selection of proteins and ligands, and their compositions are biased toward peptide and peptidomimetic inhibitors and certain protein superfamilies. In contrast, because only one protein and four ligand types are used, the lattice database should have representative ligand compositions. 

Several papers proposing multiple recognition sites for Pgp have been presented in the past. In this work, the pharmacophoric analysis of the dataset shows that the requirements to interact with Pgp are the same for all 129 compounds. Since in our database we have not included known R-site binders and anthracydines, we cannot say definitively that the pharmacophore found represents one of the binding sites that have been described in the literature. Two of the molecules present in the database, verapamil and dipyridamole, are known to bind in the H-site described by Shapiro and Ling [10]. We also cannot definitely state that the pharmacophore defines any functional site within the transporter. Further work, to try to define the location of the corresponding amino acids in a protein homology model, is in progress. 

The results confirm that species-specific determination of proteins in archival samples is possible. Egg proteins, including yolk protein, were identified, as were proteins from sheep mUk the latter were unexpected. It is suggested that it is feasible to build a database of proteotypic peptides to more readily identify binders used in paints. 

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