Oxygenation Product of Hemoglobin

The oxidation product of hemoglobin is methemoglobin while the oxygenation product of hemoglobin is-

Correct Answer: Oxy-hemoglobin

The oxygenation of hemoglobin produces Oxy-hemoglobin (HbO₂). This is a reversible process where O₂ binds to the Fe²⁺ (ferrous) iron in Hb without changing the iron oxidation state.

Key Distinction: Oxidation vs. Oxygenation

• Oxygenation: O₂ reversibly binds to Hb (Fe²⁺ remains Fe²⁺) → Oxy-hemoglobin (bright red colour)
• Oxidation: Fe²⁺ irreversibly oxidized to Fe³⁺ → Met-hemoglobin (chocolate brown colour) — this is the true oxidation product

All Forms of Hemoglobin

• Oxy-hemoglobin (HbO₂): Hb + O₂ → Bright red; 98.5% of O₂ transported this way
• Met-hemoglobin (Hb-Fe³⁺): Oxidation product → Chocolate brown; seen in nitrate/chlorate poisoning
• Carboxy-hemoglobin (HbCO): Hb + CO → Bright cherry red; CO binds 250× more tightly than O₂
• Carbaminohemoglobin (HbCO₂): Hb + CO₂ → Transports 23% of CO₂ in blood

Clinical Note

• Nitrate poisoning → Met-hemoglobin → chocolate brown blood → treat with Methylene blue IV
• CO poisoning → Carboxy-hemoglobin → cherry red skin/mucous membranes despite tissue hypoxia