Molecular Docking Study of CHS Gene from a Medicinally Important Orchid, Coelogyne ovalis Lindl.

Chalcone synthase (CHS) is an important enzyme belonging to the polyketide synthase (type III) family. It is well known for substrate specificity and catalyses diverse groups of polyketides of pharmaceutical value. In the present study, the structure of the CHS protein has been predicted from the medicinal orchid, Coelogyne ovalis Lindl. This is an evergreen orchid, well known for its medicinal uses. The homology-based model was constructed from CHS of C. ovalis (CoCHS) and 16 different ligands were used based on the specificity for molecular docking studies. The four best ligands on the basis of greater negative binding energy were found to be 3-carbomoyl-picoliniyl CoA, followed by carbomoyl-2-napthoyl CoA, p-coumaroyl CoA and malonyl CoA. The present structural study reveals that CoCHS has signature and catalytic amino acid residues, namely Cys165, Asn337, His 306, Phe216 and Phe 266. These residues are known to have a broad-range substrate profile and are responsible for the binding of protein ligands. The present study elucidates the chemical basis of CHS from C. ovalis by understanding the structural and functional relationship. This provides an insight for manipulating the enzymes, CHS-like for the synthesis of new bioactive compounds, which may further enhance the diversity of the polyketide biosynthetic family