Dynamics of proton transfer and enzymatic activity.

The rate-determining elementary reaction step, i.e. proton transfer from the chymotrypsin active centre to the scissile substrate bond had been studied in the present work. On the basis of our theoretical results a hypothesis was formulated to explain chymotrypsin enzymatic efficiency. After ES complex formation excited vibrational states are populated in the enzyme molecule. In the rate-determining elementary reaction step, the proton transfer takes place from the first excited vibrational state of the N-H bond in the imidazole group of His57. This proton transfer is realised by quantum mechanical tunneling mechanism.