Biological systems exist through a complex interplay of a diverse range of macromolecules performing specific functions. For each macromolecule, the gap between visualizing its three dimensional (3D) structure and understanding its functional properties needs to be traversed by a description of the free energy landscapes governing its activity. The function and assembly of large macromolecular complexes relies on molecular recognition of individual macromolecules by their partners and dynamic control of their interaction with substrates. The primary goal of our research is to use Molecular Mechanics (MM) based simulation methods to understand free energy landscapes describing chemical and conformational change in macromolecules and their complexes. We also aim to validate our computational predictions with structural and biochemical data through our collaborations with experimental groups