Critical role of substrate conformational change in the proton transfer process catalyzed by 4-oxalocrotonate tautomerase

4-Oxalocrotonate tautomerase enzyme (4-OT) has catalyzed the isomerization of 2-oxo-4-hexenedioate and the isomerization is studied by using the combined quantum mechanical and molecular mechanical method. The studies have shown that proton transfer process is coupled to a conformational change of the substrate and the conformation change is promoted by the changes in the electron distribution of the substrate taking place as the proton transfer has occurred.