Which enzyme class removes a phosphate group from a molecule?

• A. Phosphatase
• B. Kinase
• C. Phosphorylase
• D. Protease

Answer: (A)

Removing a phosphate group from a molecule is dephosphorylation, handled by enzymes called phosphatases. These enzymes specifically hydrolyze the phosphate ester bond, taking off the phosphate that was added during phosphorylation. Kinases, by contrast, are the ones that add phosphate groups, often using ATP as the phosphate donor to regulate activity and signaling. Phosphorylases use inorganic phosphate to cleave bonds in certain substrates, which involves phosphate but isn’t simply about removing a phosphate group from a molecule. Proteases break peptide bonds in proteins, not phosphate groups. So the enzyme class that removes a phosphate group is phosphatase.