Expert: Florence M Rollwagen - 5/15/2008

Question
What's the difference between Hemoglobin and Myoglobins O2 binding profiles?

Answer
Hi Ali:

Hemoglobin and myoglobin are oxygen carring molecules in the blood.  Myoglobin is located in the muscles, while hemoglobin transports oxygen throughout the body.

Hemoglobin exhibits co-operative binding in that the binding of one oxygen increases the affinity of oxygen for the remaining sites.  Hemoglobin is a tetramer.  In that way, hemoglobin binds oxygen very tightly when it is present in high concentrations (in the lungs).  In low oxygen concentrations, like in the tissues, hemoglobin releases its oxygen in a similar manner.

Myoglobin is a single monomer and cannot exhibit co-operativity.  That means that myoglobin is a poor transport molecule, but works very well to store oxygen in muscles for aerobic use.  Deep sea mammals like whales and dolphins have large amounts of myoglobin in their tissues and are able to stay underwater without breathing much longer than terrestrial mammals like us.

Here is an article/graph on this subject:
http://www.bio.mtu.edu/campbell/401lec17p3.html

I hope this has helped you. Please write back if you have more questions.

FM Rollwagen, PhD