General principles of enzymatic catalysis

A large group of scientists, including the author, believe that a chemical catalytic process, as well as an enzymatic reaction contains a certain sequence of elementary chemical steps. Each of these steps proceeds by ordinary laws of chemical kinetics. The accelerating action of a catalyst is accounted for by the fact that its active centers become involved in such chemical reactions with substrate molecules, which lead to an increase in the velocity of the process as a whole. Within the framework of this concept, enzymes are characterized by a set of certain specific properties, which have been polished off in the course ofbiological evolution. 

According to modem concepts, the occurrence of a catalytic reaction proceeds at a sufficient rate provided the following factors ( selection rules) are operating in concert  

The Thermodynamic Feasibility of the Process as a Whole. The change of the positive standard Gibbs energy (AG0) in an each step must not be greater than about 20-30 kJ/mole. 

Low Energy Activation in Each Step. In certain cases, the rule is, the better the thermodynamic of the step, the lower the energy activation (Polanyi-Semenov, Bronsted equations, for example). 

Among the factors determining low energy activation of elementary chemical steps are concerted and multi-electron mechanisms, mechanical stress on substrate and catalytic groups and optimum polarity of the active site cavity. 

---