Energy profiles of the catalytic cycle of enzymatic reactions and factors determining enzymatic catalysis efficiency.

Free energy profiles along the reaction coordinate were analyzed for several model systems by modeling elementary processes of the catalytic cycle of enzymes. A substantial contribution of fast non-limiting steps, which are conformational changes/adjustments, and proton transfer steps to the implementation of the catalytic cycle and high rates of enzymatic reactions is shown. The rate constants of conformational changes and proton transfer steps were determined from an analysis of the free energy profiles. In most cases, the lifetimes of the conformers lie in a range of 10−10 s. A distinctive feature of enzymatic catalysis is the multistep character of the reactions, while the catalytic cycle is accomplished in the conformationally flexible polymer matrix with the conformational adjustment of the active site of the enzyme. [ABSTRACT FROM AUTHOR]