Towards Understanding and Eliminating False Positives in Virtual Screening
Keith Davies, Scientific Director, Treweren Consultants
Date Posted: Thursday, April 10, 2008
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About the Speaker
Keith Davies has worked developing software for computational chemistry for over 25 years. He founded Chemical Design in 1983 and took the company public in 1996. In 1998, the company was acquired by Oxford Molecular (now part of Accelrys). He is motivated by innovation and in recent years has been pioneering the use of Pharmacophore technology for Virtual Screening. He has also been involved with distributing computing projections including Find-a-Drug and CANDDO in collaboration with Oxford University. His current focus is on improving the reliability of Virtual Screening predictions and analysing the results.
There are many programs which can dock molecules into receptor sites and as many scoring functions. For 80-90% of molecules that can be folded into the receptor site, most software incorrectly predicts inhibition. The approximations in the scoring functions are usually blamed. The analysis of a subset of the 68 billion drug-like molecules and nearly 300 protein targets screened in the Find-a-Drug project, suggests that improving the docking algorithms and gaining a better insight into the interactions likely to be associated with inhibition delivers substantially better results. Most scientists would expect consideration of side-chain motion to help but we were surprised to discover for a diverse series of targets that inhibitors appear occupy an 'active volume'. Molecules that utilise space outside this 'active volume' do not exhibit activity despite being predicted to do so. This paper reports examples of up to 100% of false positives being eliminated!