Question

Write a paragraph of 3-5 sentences answering the following question. Your response should first answer the question and then go on to state physiological interpretation's behind your answer. Paragraphs that demonstrate complete and thorough reasoning will receive full points.

Compared to hemoglobin, myoglobin has a lower binding affinity for O₂ and a higher O₂ binding capacity, two characteristics that allow myoglobin to efficiently provide skeletal muscle cells with a readily-accessible reservoir of O₂.

Answer 1

Myoglobin functions as an oxygen storage protein rather than oxygen transport protein like hemoglobin in the skeletal muscles because it has a very strong affinity for oxygen. Hemoglobin, in turn, has low oxygen binding capacity hence it acts as a transport protein. If Hemoglobin had been used in muscles it could not act properly as it has a low oxygen binding capacity and the oxygen has to be stored in muscles as it helps in the aerobic respiration required for contraction of muscles.

Actually, myoglobin has a proximal histidine group that helps it bind oxygen. To perform its job, myoglobin must effectively bind any oxygen released from hemoglobin. Myoglobin, therefore, needs to have a higher oxygen affinity than hemoglobin.

the hemoglobin dissociation curve is S-shaped, or sigmoidal, in character and myoglobin curve is hyperbolic which means that hemoglobin becomes fully loaded with oxygen in the lungs and fully unloads bound oxygen at the tissues where it is needed. This is not the case with the myoglobin as it has a higher affinity for the oxygen which helps it to store the oxygen in the tissues where it is present and not release it easily.