Enzyme catalysis is a process wherein the enzyme reacts with another molecule, known as a substrate. This catalysis of chemical reactions lowers the activation energy (Ea), which then provides enough energy for the reactant molecules to form a new substance. The enzyme bonds with the substrate and changes the molecule into a new product. Unlike the substrate, the enzyme remains unchanged after the process and is able to carry out multiple such processes. Another role of the enzymes is to stabilize chemical reactions as well as to act as catalysts.
A catalyst has the ability to remain whole while increasing the rate of a chemical reaction. Artificial catalysts can carry out similar chemical reactions; however, they are not as potent and cannot compete against the rate of acceleration that occurs in a natural enzyme catalysis. Enzyme catalysis in humans usually takes place at a temperature of about 37 degrees Celsius (99 degrees Fahrenheit).
Comprised of amino acid chains, the enzymes have a three-dimensional shape that is easily altered by high temperatures and an imbalance in the potential hydrogen, also known as the pH balance. Certain chemicals, free radicals, and heavy metals can also change the shapes of enzymes and interfere with enzyme catalysis. If the enzyme loses its shape, it is no longer able to carry out the catalysis of biochemical reactions.
The most favored model of enzyme catalysis is the induced fit model in which the substrate interlocks with a small active area on the enzyme, known as the active site. Once the bond is completed, a new product is released from the active area. During the bonding process, the enzyme slightly changes in shape, but as the new product is released, the enzyme is ready for the next chemical reaction to take place.
Differential and uniform binding are the primary ways in which binding occurs. Differential binding consists of only strong transition binding. Uniform binding, on the other hand, includes both strong substrate and transition state binding. Both mechanisms can take place when small substrate unbound enzymes are present.
Differential binding, however, is essential for lowering the Ea when the enzymes are saturated, in other words, have a high affinity, which is is the most common mechanism as most enzymes work this way. After the bond has formed, the energy of the transition state is reduced, and an alternative route is provided for the chemical reaction to take place. Thereby, the enzyme catalysis is able to remain stable.