Enzymatic catalysis as a process controlled by protein conformational relaxation.

Great progress in studies of protein dynamics in the past decade propels an essential alteration in our understanding of the enzymatic catalysis phenomenon. A careful analysis of assumptions made by the hitherto used conventional theory of chemical reactions shows that neither of them is in fact satisfied. One of the reasons is the presence of a slow interconformational dynamics within the protein native state. In consequence, the simple classical statement "enzymes accelerate reactions by decreasing the free energy of activation" represents only half of the truth. Enzymatic reactions actually proceed through 'gates' of relatively low free energy but it is not the process of activated gate crossing that limits the reaction rate, but the process of generally non-activated gate opening, controlled by the conformational relaxation. Possible consequences of this fact are pointed out.