Urease (EC 3.5.1.5) is an enzyme that catalyzes the hydrolysis of urea into carbon dioxide and ammonia. The reaction occurs as follows: (NH₂)₂CO + H₂O → CO₂ + NH₃

In 1926 James Sumner shows that urease is a protein. Urease is found in bacteria, yeast and several higher plants.

Characteristics:

• Molecular weight : 480 kDa
• Optimum pH : 7.4
• Enzymatic specificity: urea and hydroxyurea
• Inhibitors : heavy metals, sodium, potassium

A specific urease (which may be used in diagnosis) occurs in Helicobacter pylori.