Enzyme Kinetics - Activation Energy

Activation Energy

Enzyme kinetics is simply a specialized branch of chemical kinetics. As such it is based on the kinetic theory of matter. In this theory a solution is viewed as being made up of a group of molecules all moving at particular velocities. As they move about they collide with each other, and each such collision involves a certain amount of energy. If the energy is sufficient, the molecules combine to form an activated metastable intermediate, some times referred to as the transition state. The energy which is required for the formation of this intermediate is the activation energy. If the collision does not involve sufficient energy no reaction occurs, i.e. the molecules just bounce off.

An energy profile of the reaction

where B* is the transition state, can be drawn:

In an enzyme catalyzed reaction, the enzyme binds to the transition state (reaction intermediate) better than the ground state (substrate) thereby lowering the energy level of the transition state, and therefore the activation energy. In an enzyme catalyzed reaction, we have:

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