Which of the following enzymes adds a phosphate group to target proteins?

• A. Ligase
• B. Kinase
• C. Phosphatase
• D. Amylase

Answer: (B)

Verified step by step guidance

1. Understand the role of enzymes in cellular processes. Enzymes are proteins that catalyze biochemical reactions, often by lowering the activation energy required for the reaction.
2. Identify the function of each enzyme listed in the problem. Ligase is an enzyme that joins two molecules together, often using ATP. Phosphatase is an enzyme that removes phosphate groups from proteins. Amylase is an enzyme that breaks down starch into sugars.
3. Focus on the enzyme 'Kinase'. Kinases are a specific type of enzyme that catalyze the transfer of phosphate groups from high-energy molecules like ATP to specific substrates, typically proteins.
4. Recognize that the addition of a phosphate group to a protein is known as phosphorylation, a key regulatory mechanism in cellular signaling and function.
5. Conclude that the enzyme responsible for adding a phosphate group to target proteins is a kinase, as it facilitates phosphorylation by transferring phosphate groups.