Enzymes are protein catalysts, which means that they help to speed up chemical reactions without being consumed in the process. The names of enzymes usually end in -ase. Chemical change takes place when the bonds between the atoms of reactant molecules break and product molecules are formed by a rearrangement of atoms. Reactant molecules collide with enough force, past their activation energy (EA) and causes breaking to occur between the bonds. When there is an increase in temperature, the rate of most reactions increase, but proteins are denatured at high temperatures and that is no good for the cell. Therefore, cells rely on enzymes to speed up reactions at moderate temperatures. An example of an enzyme is amylase, which catalyzes the breakdown of amylose into maltose subunits. 

Active site - The location where the substrate binds to an enzyme. 

The active site of an enzyme is usually a pocket or a groove in the 3D structure of the protein. In order for binding to occur, the substrate and active site must have the same shape. The induced fit model of enzyme-substrate interaction is when a substrate enters the active site and its functional groups come close to the functional groups of a number of amino acids, therefore causing the protein to change its shape to better accommodate the substrate. 

*Enzymes do NOT affect the energy change of a reaction, it just decreases the potential energy level of the transition state and allows the reaction to progress further. 

​

Feedback inhibition - Used to control metabolic pathways involving a serieds or sequential reaction, each catalyzed by a specific enzyme. 

In Feedback inhibition, 

Enzymes are controlled by: 

- pH

- Temperature

- Concentration of enzyme

- Concentration of substrate

- End production inhibiion

- Steric inhibition

- Allosteric inhibition