Rational drug design: the search for Ras protein hydrolysis intermediate conformation inhibitors with both affinity and specificity.

Computer-aided drug design (CADD) plays significant roles in all stages of today's drug discovery. Many CADD technologies and methods were employed in finding promising hits against different targets during the past several decades. In this review, the most common molecular modeling methods applied to computer-aided drug design are discussed. However, how to effectively integrate these computational methods and then combine them with experiments to improve the hit rate is still a challenge. In addition, the present study reviews the ISR (intrinsic specificity ratio) as a novel concept and quantitative criterion for binding specificity to be applied as a complement in addition to binding affinity for finding new leads. Using Ras protein as a case study, Molecular modeling calculations and the subsequent biological testings for the hits are performed, the specificity of these hits is also studies against the normal and cancer cells aiming at discovering the novel chemical compounds with minimal side effects. Herein, the case study also includes the evaluations for tumor-specific cytotoxicity on different cell lines. The current results suggest that ISR is useful for quantitative assessment of specificity of small molecules.