B.11B_Enzymes_approaching – 03

The reactant, or substrate, binds briefly to a special area on the enzyme molecule called the active site. The active site will change slightly to fit the substrate. This action is like the change of your grip when you shake another person’s hand. The slight change places the substrates into the position needed for the reaction to take place.

The bonds of the substrates are stretched in the active site. This weakens the bonds of the substrates. It lowers the amount of energy needed to change the substrates to products. The products break away from the enzyme. The active site is now free for another substrate to briefly bind to it and repeat the process.

 

 

Enzymes are large protein molecules folded into very specific 3D shapes. The function of the enzyme depends on its structure. Only certain reactants can bind to the specific shape of the enzyme. The enzyme is specific for a reactant just as a lock is specific to a key. For example, the enzyme that breaks down lactose will not break down similar sucrose or maltose molecules.

The lactase enzyme is specific for the reaction that breaks down lactose into simple sugars that can be used by cells. Lactase is produced in the small intestines of humans and other mammals. Lactase molecules are shaped to fit only lactose molecules. When mammals drink milk, lactose will be broken down by the lactase enzyme in the small intestines.

 

People who are lactose intolerant do not produce enough lactase to break down the lactose that they eat and drink. The lactose molecules cause pain as they make their way through the intestines. The lactase enzyme in Ben’s pill breaks down lactose just like naturally produced lactase. This takes away some of the pain that lactose intolerance can cause. It also allows Ben’s cells to take in the important simple sugars that are produced when lactose is broken down.

There are many inherited disorders that are caused by not having enough of an enzyme. Some of the disorders, like lactose intolerance, are caused by a lack of enzymes that break down foods. This robs the organism of important energy molecules. It also robs the organism of raw materials to build more cells. There are other inherited disorders caused by a lack of enzymes that break down cellular wastes. Over time, harmful amounts of the wastes build up in cells, tissues, and organs.

Enzymes are found in all cells of organisms. They are important molecules with very specific structures that provide very specific functions. They allow chemical reactions to occur quickly under the normal conditions in an organism. Enzymes play an important role in every cellular process.