[en] Modification of trypsin from bovine pancreas was studied to understand the biomolecular interactions between the protein and ligand, toward metal ion. A semisynthetic complex of trypsin-1,10-phenanthroline (trypsin-PHN) was prepared and investigated for its role in the hydrolysis of azocasein. Predicted results from molecular docking studies aid in the comprehension of the protein-ligand system. PHN ligand demonstrated the ability to provide more sites for interactions with metal ions and contribute extensively to the development of a new generation of industrial biocatalysts. The trypsin-PHN complex had an increment of 40 % activity in the hydrolysis of azocasein. In the presence of 5 μM Ca²⁺ ions the activity was higher than native enzyme but decreased in the presence of Mg²⁺, Zn²⁺ and Fe²⁺ ions, thus, providing additional insight into potential inhibitors of the rational enzyme design. (author)