Urease

Urease is a special enzyme that contains the metal nickel. Its main job is to break down a chemical called urea into ammonia and carbon dioxide. This reaction is important for the nitrogen cycle, which is how nitrogen moves through the environment and living things. Urease is found in many living organisms, like bacteria, fungi, plants, and some animals. It helps them use urea to get the nitrogen they need to grow and survive. In soil, urease helps turn nitrogen from dead plants and animals into forms that plants can use, which helps crops grow better. Because of its role in breaking down urea, urease is important in many areas, including medicine, farming, and protecting the environment.^[2][3]

In 1926, the scientist James B. Sumner made a big discovery when he was the first to take an enzyme from a plant and turn it into crystals. He got this enzyme, called urease, from a plant known as the jack bean. This was a huge moment in science because it proved that enzymes are actually proteins. For this important work, Sumner won the Nobel Prize in Chemistry in 1946. Since then, urease has become a model enzyme that scientists study to learn more about how enzymes work.^[2][3] Urease works by grabbing onto a chemical called urea at a special spot called the active site. Two nickel atoms in the enzyme help start the reaction. Urease breaks down urea into carbon dioxide (CO₂) and ammonia (NH₃).

(NH₂)₂CO + H₂O → CO₂ + 2NH₃

This happens in two steps. First, urease helps turn urea and water into one ammonia molecule and a compound called carbamic acid. Then, carbamic acid quickly falls apart into another ammonia molecule and carbonic acid. Carbonic acid can mix with water to form carbon dioxide and a substance called bicarbonate. As more ammonia builds up, it makes the surrounding area more basic, or less acidic. This increase in pH can affect the environment around the enzyme, and sometimes even cause problems in the body or in soil.^[4]

In medicine and farming, urease plays an important role, both helpful and harmful. Some bacteria that make people sick, like Helicobacter pylori, Proteus mirabilis, and Ureaplasma urealyticum, use urease to survive and cause disease. For example, H. pylori lives in the human stomach, where it is very acidic. Urease helps the bacteria make ammonia, which cancels out the acid. This lets the bacteria live there, but it can also lead to stomach problems like inflammation, ulcers, and even stomach cancer. Doctors use this to help find H. pylori. One test, called the urea breath test, checks for urease activity to see if the bacteria are present.^[4] In urinary tract infections caused by bacteria that make urease, too much ammonia can damage the kidneys and even lead to kidney stones.^[5] In farming, urease is found in soil and can affect how well fertilizers work. Many fertilizers contain urea, and if urease breaks it down too quickly, nitrogen can escape into the air as ammonia gas. This wastes fertilizer and harms the environment. To fix this, farmers use special chemicals called urease inhibitors. These slow down the reaction so crops can absorb more nitrogen. Urease is also used in science tools called biosensors. These tools can measure how much urea is in things like blood, urine, or soil, which helps in both medical and environmental research.^[6]