Enzymes are primarily complex proteins. They are necessary for life and regulate almost all the biochemical reactions in living things, from microorganisms to apex predators. Enzymes are catalysts that speed up chemical reactions without being altered.

In addition to various bodily functions, enzymes also have industrial uses, such as removing proteins from contact lenses, removing stains from laundry, and pretreating biomass for biofuels. The cell's chemists, as enzymes are known, have multiple jobs to do, as you'll see below.

Enzyme History

Scientists didn't discover enzymes til the mid-19th century. The word "enzyme" came into use in 1878, derived from Greek words meaning "in yeast" because they were discovered while researchers were studying fermentation.

Louis Pasteur, the man who gave us pasteurized milk and early vaccines, was among the first to realize that fermentation was the result of a cell component.

concept word enzyme on cubes on a blue background Zhanna Hapanovich/ Getty Images


What Are Enzymes Made Of?

Enzymes exist in every cell—they have different compositions depending on the type of cell they occupy. They also vary in number, although the average mammalian cell contains approximately 3,000 enzymes. Enzymes comprise amino acid chains called polypeptide chains. The amino acid sequence differs, creating multiple types of enzymes for a wide range of activities.

Colorful chain of amino acids or bio molecules called proteins - 3d illustration Christoph Burgstedt/ Getty Images


Enzyme Activity

Enzymes break down the foods we eat so the body can make the most use of them, and they're present in saliva and gastric juice. They're also found in blood and are responsible for blood clotting.

Enzymes affect metabolism and how muscles and energy work. They help form large molecules from small ones to make cells and play an essential role in reproduction, respiration, nerve function, and other vital processes.

CRISPR-Cas9 genome editing enzyme, 3d illustration Artur Plawgo/ Getty Images


How Do Enzymes Function?

Enzymes go to work on molecules called substrates, which bind to a part of the enzyme known as the active site. Two theories explain this interaction. The lock and key theory suggests that the active site is specifically shaped to hold certain substrates. The induced-fit model posits that each component alters its shape to connect.

However it works, when they link up, a chemical reaction forms a new product, and the enzyme can detach and move on.

Close-up of fingers inserting a key into a door lock SilentWolf/ Getty Images


Factors That Affect Enzyme Activity

Temperature, pH, substrate concentration, and inhibiting molecules can affect enzyme activity. For example, enzymatic reactions speed up when there's an increase in substrate concentration, but exposure to excessive heat leads to a loss of shape and to dysfunction.

Certain enzymes prefer an acidic pH, while others prefer an alkaline one. There are also scenarios where molecules similar to the substrate connect to an enzyme's binding site.

Wooden thermometer with red measuring liquid showing high temperature over 36 degrees Celsius on sunny day on background of apple tree digihelion/ Getty Images


Types of Enzymes

Every day, trillions of chemical reactions occur in our bodies. There are three core categories of enzymes:

  • Metabolic enzymes run the show
  • Digestive enzymes break down food
  • Food enzymes exist in raw foods and trigger digestion.

partial view of woman holding paper made large intestine on grey background LightFieldStudios/ Getty Images


Specific Examples of Enzymes

Amylase breaks down starches, and lipase breaks down fats and oils—which makes it excellent for dishwashing. Protease breaks down proteins, and creatine kinase (CK) assists muscles in making energy.

DNA polymerase enables DNA's copy-paste function for growth, and thrombin makes it possible for the blood to clot and wounds to heal. Lysozyme wrecks cell walls to kill bacteria.

A RNA polymerase (yeast) is composed of several proteins. It unwinds DNA strands (violet) and builds RNA (red) out of the nucleotides uridine, adenosine, cytlidine and guanosine monophosphate. selvanegra/ Getty Images


Coenzymes and Cofactors

Two types of cofactors exist: inorganic ions and coenzymes. Coenzymes or cosubstrates generally come from vitamins or other essential nutrients; they are helper molecules that support an enzyme, helping it catalyze a chemical reaction.

chemical formula of coenzyme Q10 cacaroot/ Getty Images


What Are Dietary Enzyme Supplements?

Digestive enzymes can help with food processing and nutrient absorption and symptoms such as heartburn and loose stools. The pancreas makes digestive enzymes like amylase and sucrase, but enough people have deficiencies in these nutrients that many supplements are available. However, don't take digestive enzymes without consulting your doctor.

woman holding a glass of water and taking vitamins and pills on a light background. close up. choi dongsu/ Getty Images


Enzymes and Disease

We run into health problems when our bodies lack enzymes. Lactose intolerance is a common condition these days, occurring when a person has low levels of lactase, the enzyme that breaks down the lactose in milk. People with Tay-Sachs disease, for instance, experience a harmful buildup of fatty protein in the brain because they are lacking a vital enzyme.

Woman having bad stomach ache with a glass of milk, Lactose intolerance, health care concept kitzcorner/ Getty Images


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