The affinity of hemoglobin for oxygen is less than its structural analog myoglobin. However, this does not affect hemoglobin's usefulness for the body; on the contrary, it allows hemoglobin to be a more efficient carrier than myoglobin. This is because hemoglobin can release oxygen more easily than can myoglobin. It is both important for oxygen to be carried to different areas and also to be released when needed. The higher affinity of a given protein for oxygen, the harder it will be for that protein to release oxygen when needed. Therefore, hemoglobin's lower affinity for oxygen serves it well because it allows hemoglobin to release oxygen more easily in the body.
