eHiTS ® : Electronic High Throughput Screening
eHiTS_Score

eHiTS 2009 Binding Affinity Prediction technical note.
To see other eHiTS 2009 technical notes, visit our recently updated technical notes pages.

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eHiTS has a novel scoring function that takes advantage of temperature factor information provided in PDB files to give a more complete picture of interactions.  All atoms in a PDB file have a temperature factor (B) associated with them.  This temperature factor indicates the how much the atom varies from the mean position.  Some atom positions are very precisely defined while others vary greatly, this has a very strong influence on the weight that should be assigned to the position. The novel approach in eHiTS uses the probability of the atom position during the statistic collection to create a statistically derived empirical scoring function. The eHiTS scoring function provides a scoring function that is smooth, and accurately represents a wide variety of problems at hand.

One of the most recent studies with eHiTS Score 2009 was done using the PDBBind-2008 dataset. Please see a picture below for correlation of eHiTS Score to the experimental binding affinity. 

and a comparison with some other published results:

More details on this can be found in the eHiTS 2009 Binding Affinity technical note.

To see the effect of the eHiTS scoring function on the docking itself many studies were performed. Some were comparative studies to other previously published docking results, another study was designed by the developers of eHiTS, and that was performed on a set of 1586 protein ligand complex files taken from the PDB database.  These codes were selected as a combination of the GOLD validation set, the PDB-bind 2004 set and augmented with some more codes from the PDB, filtered  with the Lipinski rules for the ligands. In 100% of the cases, eHiTS was able to reproduce the X-ray crystal pose within 2.5 Angstrom RMSD for the top ranking (scoring) pose found and the average top-ranking RMSD for the entire set was 1.1 Angstrom. The closest RMSD was 100% under 2.0 Angstrom and the average for the entire set was 0.73 Angstrom. This high level of accuracy has never been seen before in any docking program !   For more details of these validation studies please click here.