Hemerythrin is an oligomeric iron-containing protein of the metalloprotein class found in the blood of some invertebrates. Able to reversibly bind with oxygen, ensuring its transfer to tissues. Hemerythrin is used to transport oxygen in the blood of brachiopods, sipunculids, priapulids, and some annelids (polychaetes). Here we are interested in how hemerythrin carries oxygen, so unlike the hemoglobin we use, in which oxygen is transferred directly, here oxygen is not transferred by itself, but in the form of a special compound HO2 or -OHH, which ultimately gives an interesting feature: our hemoglobin is good associates not only with oxygen, but also with carbon monoxide that is released during combustion (often during a fire, people die precisely because of carbon monoxide poisoning, and only after that because of burns), but hemerythrin, due to its peculiarity in terms of capture oxygen, it does not bind to carbon monoxide, so if I understand correctly if we had gemerythrin instead of hemoglobin, we would not be exposed to the action of carbon monoxide.
And here we come to the heart of my question: what problems can arise when using hemerythrin as an oxygen carrier instead of hemoglobin?
The main problems in this question include: the efficiency of oxygen transfer and how many things will need to be rearranged in the human body.