Which of the following enzymes does not belong to the hydrolase class?

Which of the following enzymes does not belong to the hydrolase class?

• A. Alkaline phosphatase
• B. Aldolase
• C. Amylase
• D. Lipase

Answer: (B)

Hydrolases are enzymes that use water to break chemical bonds, performing hydrolysis. Aldolase, on the other hand, catalyzes cleavage of a carbon–carbon bond in fructose-1,6-bisphosphate to form two triose phosphates, which is a lyase-type reaction that breaks bonds without incorporating water. Lyases remove groups or add them to double bonds and often cleave C–C bonds, not through hydrolysis. The other enzymes listed are classic hydrolases: alkaline phosphatase removes phosphate groups by hydrolysis; amylase hydrolyzes glycosidic bonds in starch; lipase hydrolyzes ester bonds in lipids. Therefore, aldolase does not belong to the hydrolase class.

Hydrolases are enzymes that use water to break chemical bonds, performing hydrolysis. Aldolase, on the other hand, catalyzes cleavage of a carbon–carbon bond in fructose-1,6-bisphosphate to form two triose phosphates, which is a lyase-type reaction that breaks bonds without incorporating water. Lyases remove groups or add them to double bonds and often cleave C–C bonds, not through hydrolysis. The other enzymes listed are classic hydrolases: alkaline phosphatase removes phosphate groups by hydrolysis; amylase hydrolyzes glycosidic bonds in starch; lipase hydrolyzes ester bonds in lipids. Therefore, aldolase does not belong to the hydrolase class.