You can view known complexes for which crystal structures exist by downloading the structure files from the protein data bank (PDB) and examining them in a structure viewer such as PyMOL, UCSF Chimera, VMD, or YASARA.

If esterase-substrate complexes of interest are not in the PDB, you can download esterase files of interest and carry out docking with various substrates using programs such as Autodock or VINA.

Dear Anam Tariq,

Look the link, maybe useful.

http://www.sciencedirect.com/science/article/pii/S1044030503007645

Regards, Shafagat