The carbon dioxide molecules form a carbamate with the four terminal-amine groups of the four protein chains in the deoxy form of the molecule. Thus, one hemoglobin molecule can transport four carbon dioxide molecules back to the lungs, where they are released when the molecule changes back to the oxyhemoglobin form.

How is carbon dioxide transported in the blood by binding?

Carbon dioxide is transported in the blood from the tissue to the lungs in three ways:1 (i) dissolved in solution; (ii) buffered with water as carbonic acid; (iii) bound to proteins, particularly haemoglobin. Approximately 75% of carbon dioxide is transport in the red blood cell and 25% in the plasma.

Does carbon dioxide compete for hemoglobin binding?

Hemoglobin, an iron-containing part of a red blood cell, usually has no preference over oxygen or carbon dioxide. In other words, oxygen and carbon dioxide don’t compete when attaching to hemoglobin. This is because oxygen binds to the iron atoms in the protein while carbon dioxide binds to the protein chains.