Molecular docking and 3D QSAR studies of Chk2 inhibitors.

Isothiazole-carboxamidines are potent ATP competitive checkpoint kinases (Chk2) inhibitors. Three-dimensional quantitative structure-activity relationship models were developed using comparative molecular field analysis and comparative molecular similarity indices analysis. The study was performed using three different geometrical methods. In geometrical method-1, molecules were fully optimized by PM3 Hamiltonian and aligned using common substructure. This alignment was subsequently used for Ligand-based comparative molecular field analysis and comparative molecular similarity indices analysis. In receptor-guided analyses, the receptor coordinates were obtained from public domine (PDB 2cn8). The molecule-7 was docked into receptor protein using FlexX and two plausible binding modes were identified. These modes were used as templates for geometrical method-2 and 3. These methods were used for 3D QSAR. The geometrical method-3-based comparative molecular field analysis (q(2) = 0.75, r(2) = 0.87 and r(2) (predict) = 0.81) and comparative molecular similarity indices analysis (q(2) = 0.90, r(2) = 0.96 and r(2) (predict) = 0.75) gave better result. The steric, hydrophobic and hydrogen bond donor fields effects significantly contribute to activity. In this way, the receptor-guided study presents a more detailed understanding about chk2 active site interactions. The study indicated some modifications to the active molecule which might be valuable to improve the activity.