Mechanism of Enzyme

How does an enzyme speed up a reaction? Perhaps this question can be answered by describing the events that occurred, if a compound A (substrate) spontaneously converted into compound B (outcome), initially without enzymes and with enzymes

In a number of molecules of compound A at a given temperature there is an average kinetic energy of certain. 
Although most molecules have an average kinetic energy, some molecules have higher kinetic energy and lower than the average kinetic energy, because the molecules collide. These molecules are called molecular "energy rich" and "energy poor". Due to changes in AB spontaneous reaction, the average kinetic energy of molecules A higher than average kinetic energy of molecules B. But only the molecules A rich energy is able to react and converted to molecules B. Therefore, only a few molecules at a certain time, as a result of collisions of molecules that can reach the level of energy needed to be able to react. Energy above the average it takes A to react can be converted into B is called the activation energy. B can also be converted into A, but the activation energy for reaction B A higher because of lower energy state B compared with A.The enzyme will lower the activation energy of a reaction. If the activation energy for the reaction is low, more molecules of A (substrate) can react than without the enzyme. Enzymes increase the overall reaction rate without changing the reaction temperature. 
During the passage of the reaction, while the enzyme and substrate combine to form enzyme-substrate complex. Enzyme-substrate complex was first hypothesized by Fischer, who estimates that between enzyme and substrate occurs unity rigid like a key and the key (Figure 23). The substrate is a key complement to the enzyme or the shape of keys. Parts of the enzyme substrate combination is called the active site.If the complex enzyme-substrate complex is formed, is activated to form the reaction results. Once formed, the results are no longer in accordance with temapt active and released and the active site ready to accept another substrate molecule. 
In contrast to the rigid arrangement of the active site, Koshland estimate that the enzyme and its active site structure that is physically more flexible than had been described beforehand. Koshland describe the dynamic interactions that occur between the enzyme and substrate. If the substrate combines with the enzyme, substrate induces changes in the structure (confirmation) so that the function of the enzyme active site catalysis of the enzyme take place very effectively. This reasoning is known as the hypothesis of "induced fit" (hypothesis corresponding reduced). In some circumstances, the structure of the substrate molecule also changes during the induced fit, so the enzyme-substrate complex more functional