Reaction of Haemoglobin With CO or CN Ion

Reaction of Haemoglobin With CO or CN⁻

Haemoglobin combines with CO or CN ion to form carboxy haemoglobin by replacing water molecules. The carboxy haemoglobin is 400 times more stable than oxyhaemoglobin so that CO can displace O₂ from the latter leading to toxic effect on the human system.
The high stability of carboxyhamoglobin (brighter red than the normal haemoglobin) renders the haemoglobin incapable of performing its oxygen carrier function. If the concentration of CO in atomospheric oxygen is 10 ppm for 8 hours, the person becomes unconscious and his 35% haemoglobin has been converted to carboxyhaemoglobin. If the concentration of CO in atomospheric oxygen is 300 ppm for 4 hours the person may die and his 60% haemoblobin has been converted to carboxyhaemoglobin.

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