Computational docking operation is a useful vehicle for investigating the interaction of a protein receptor with its ligand and revealing their binding mechanism as demonstrated by a series of studies [18, 46, [76] [77] [78] [79] [80] [81] [82] [83] [84] . Docking plays a significant role in predicting binding orientation and affinity of small molecule drug candidates to their protein targets with known 3D structures [85, 86] . Hence, docking serves as an important tool in the rational computer-assisted drug design [87, 88] . GOLD 4.1 (Genetic Optimization for Ligand Docking) from Cambridge Crystallographic Data center, UK uses a genetic algorithm for docking ligands into protein binding sites to explore the full range of ligand conformational flexibility with partial flexibility of protein [89] . In this study, it has been utilized for the docking of training set compounds along with the new hits retrieved from chemical databases. Protein coordinates from the crystal structure of chymase co-crystallized with β-ketophosphonate (PDB ID: 1T31), determined at a resolution of 1.9 Å were used to define the active site [9] . All the water molecules present in the protein were removed and hydrogen atoms were added. The active site was defined with a 10 Å radius around the ligand present in the crystal structure. At the end of the computation, the 10 top-scoring conformations of every ligand were saved. Early termination option was applied to pass over the genetic optimization calculation when any five conformations of a particular compound were envisaged within an RMS deviation value of 1.5 Å. The GOLD fitness score is calculated from the contributions of hydrogen bond and van der Waals interactions between the protein and ligand, intramolecular hydrogen bonds and strains of the ligand. The protein-ligand interactions were scrutinized by DS.