Question

We discussed the relationship between the structure of hemoglobin and its function. Briefly discuss how the structure of hemoglobin make it a much better oxygen transport and delivery molecule than myoglobin.

Answer 1

The affinity of hemoglobin for oxygen is less than its structural analog myoglobin. Interestingly enough, however, this does not affect hemoglobin's usefulness for the body; on the contrary, it allows hemoglobin to be a more efficient oxygen carrier than myoglobin. This is so because hemoglobin can release oxygen more easily than can myoglobin. While it is important for oxygen to be carried to different areas of the body, it is even more important for the oxygen to be released when needed. The higher the affinity of a given protein for oxygen, the harder it will be for that protein to release oxygen when the time comes. Thus, hemoglobin's lower affinity for oxygen serves it well because it allows hemoglobin to release oxygen more easily in the body. Myoglobin, on the other hand, has a significantly higher affinity for oxygen and will, therefore, be much less inclined to release it once it is bound. Thus hemoglobin's lower affinity for oxygen relative to myoglobin allows it to have a higher overall efficiency in binding and then releasing oxygen species. For this reason, the body tends to use hemoglobin more often for oxygen-distributing purposes, although myoglobin is used as well, particularly for carrying oxygen to muscle cells.