Which statement correctly describes a metalloprotein?

Which statement correctly describes a metalloprotein?

• A. Contains a metal ion as part of its prosthetic group
• B. Contains carbohydrate only
• C. Contains lipid only
• D. Is not a protein

Answer: (A)

Metalloproteins are proteins that depend on a metal ion bound tightly to the protein, usually as a prosthetic group, for their function. That metal ion participates directly in activity—such as catalysis or electron transfer—and remains part of the protein during its action. For example, zinc in carbonic anhydrase, iron in hemoglobin’s heme, and various metals in other enzymes all illustrate how the metal ion is essential for function. So the defining feature is the presence of a metal ion as part of the protein’s prosthetic group. Statements claiming the protein is composed of carbohydrate only, lipid only, or that it isn’t a protein miss the central idea, since metalloproteins are still proteins that rely on a metal ion for their activity.

Metalloproteins are proteins that depend on a metal ion bound tightly to the protein, usually as a prosthetic group, for their function. That metal ion participates directly in activity—such as catalysis or electron transfer—and remains part of the protein during its action. For example, zinc in carbonic anhydrase, iron in hemoglobin’s heme, and various metals in other enzymes all illustrate how the metal ion is essential for function. So the defining feature is the presence of a metal ion as part of the protein’s prosthetic group. Statements claiming the protein is composed of carbohydrate only, lipid only, or that it isn’t a protein miss the central idea, since metalloproteins are still proteins that rely on a metal ion for their activity.