Compared to hemoglobin, myoglobin has a higher affinity for oxygen.

• A. Lower
• B. Higher
• C. Similar
• D. No affinity

Answer: (B)

Oxygen binding affinity reflects how tightly a protein holds onto oxygen, matching its role in the tissue. Myoglobin, found in muscle, is a single-chain protein with one heme group, so it binds O2 without cooperativity. This gives it a hyperbolic binding curve and a much lower P50, meaning it holds onto oxygen even when oxygen levels are low. That high affinity lets myoglobin take up oxygen from blood in the lungs and, more importantly, release it only when the oxygen tension inside muscle drops enough to demand it for respiration.

In contrast, hemoglobin is a tetramer whose oxygen binding is cooperative and is actively modulated by factors like pH, CO2, and temperature, which lower its affinity in tissues to promote oxygen delivery. Because of these differences, myoglobin’s affinity for oxygen is higher than that of hemoglobin, making the statement true.