Which enzyme category is known for introducing or removing double bonds (creating double bonds)?

• A. Lyase
• B. Oxidoreductase
• C. Transferase
• D. Hydrolase

Answer: (A)

Lyases are enzymes that create or remove double bonds by eliminating small molecules or by adding groups to a bond, without involving water-driven hydrolysis or redox reactions. This ability to form or remove a C=C bond is a defining feature. A classic example is enolase, which converts 2-phosphoglycerate to phosphoenolpyruvate by removing water and forming a carbon–carbon double bond.

Hydrolases cleave bonds using water, not by forming double bonds. Oxidoreductases drive electron transfer, changing oxidation states rather than making or breaking a double bond. Transferases move functional groups from one molecule to another. Because only lyases routinely generate or remove double bonds during their reaction, they fit the description.