The main purpose of porphyrins in the body is to

• A. Contribute to the synthesis of heme
• B. Carry oxygen to the tissue
• C. Transport iron
• D. Combine with free hemoglobin

Answer: (A)

Porphyrins provide the framework for making heme, the iron-containing prosthetic group that sits at the heart of many critical proteins. In the body, the porphyrin ring coordinates iron to form heme, which then partners with globin to enable oxygen binding in hemoglobin and myoglobin and serves in various enzymes like cytochromes. So the primary role of porphyrins is to contribute to the synthesis of heme, the component that actually carries out these essential tasks. The other options describe functions that depend on heme after it’s formed, not on porphyrins themselves.