How Do Enzymes Work?

In biology, an enzyme is defined as a type of protein that catalyzes the rate at which chemical reactions occur. When something catalyzes a reaction that means that it increases the rate at which the reaction occurs. Commonly speaking, enzymes increase the speed of reactions.

The fact that enzymes are proteins means that enzymes are a type of organic compound. However, more specifically, enzymes are organic compounds that are composed of amino acids. These amino acids are assembled in a systematic and specific order in a chain. The amino acids are then folded in a specified manner

There are three different types of enzymes. There are digestive, metabolic, and food enzymes. Digestive and metabolic enzymes are produced by the cells of the body. Food enzymes are derived from the food that we consume.

Cells facilitate the production of the digestive and metabolic enzymes. Since enzymes can widely differ from each other (for example, the enzymes used in the digestion process are not the same as the enzymes used in the process of blood clotting), the cells need to know which enzymes to produce. The genes of a cell specify the instructions for how to build the required enzyme. 

Some of the enzymes that are vital to the digestive process include pepsin, and trypsin. These enzymes help break down proteins in the digestive track, and convert them into amino acids. The enzyme cellulase comes from certain food that we eat. Cellulase is responsible for aiding in the digestion of fibers.

Enzymes' Roles

Enzymes have a hand in almost all processes in the human body. As mentioned above, enzymes have a part in digestion, in the breaking down of vitamins or nutrients that you ingest, in building cells, and in reactions that transform energy into a usable source for the body.

Enzymes are extremely specific, and since different enzymes have such specific and varied tasks, it is not yet understood exactly how enzymes work.

Enzyme Action Theories

Scientists know that when enzymes facilitate a reaction, they must interact with a specific target. This target is called a substrate. After the enzyme interacts with a substrate, the substrate is then converted into a useable end product.

One theory is that enzymes operate in a type of “lock and key”  mechanism. This means that an enzyme and a substrate are complementary to each other. Similar to how a key can only work in a specified lock, an enzyme can only work with a specific substrate. Vice versa, substrates cannot work with more than one enzyme.

The fact that enzymes have a particular location that bonds to different substrates supports this theory. This location is referred to as an “active site.” When the enzyme and the substrate fit together, they form an enzyme substrate complex (the enzyme is the lock and the substrate is considered the key).

An alternate theory, called the induced site theory, suggests that the substrate actually modifies its shape as it connects with the enzyme. However, neither of these theories fully explain how all the different types of enzymes operate, and all their different reactions occur.