Normally, when there is a mutation on the residue of a ligand, it causes the folding to change. This will then causes the protein to not being able to bind to the ligand. If we were to study the interaction between both the proteins by studying the hydrogen bonds that exist between them, how can we explain if there still exist a h-bond between both the protein and ligand when one of the residue is mutated?
Experimental results has proven that when that particular residue (Leu) is mutated into another residue (Phe) for that ligand I am studying, there was a reduction in that protein's activity. But why still a h-bond in between?