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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.

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    $\begingroup$ I strongly suspect such a specific biology question would do better in a biology or biochemistry specific stackexchange. Here, if you tell us the pros and cons, we can tell you how it will affect your world. but for the nitty gritty biochemistry? not so much. $\endgroup$
    – PcMan
    Dec 25 '20 at 18:56
  • $\begingroup$ The essence of my question is to replace hemoglobin with hemeritrin in human blood in order to avoid carbon monoxide poisoning, if you know other solutions to this problem, I am listening to you. I repeat: we are talking about genetically modified people. $\endgroup$ Dec 25 '20 at 19:02
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    $\begingroup$ @PcMan The other Stacks tend to be quite literal. In other words, it's very common for them to close or migrate questions like these because the question is fanciful. It's not uncommon for them to migrate questions like this to us. $\endgroup$ Dec 25 '20 at 19:06
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It might work well!

I initially thought - no way. This molecule is for cold blooded creatures living in low oxygen environments. It is going to be burnt by our high O2 environment and will not deliver O2 adequate for our hot muscles.

To my surprise I found a bunch of stuff about using hemerythrin as a blood substitute!

Towards the Development of Hemerythrin-Based Blood Substitutes

Our results indicate that chemically modified Hrs constitute a promising alternative candidate for blood substitutes. Hr undergoes minimal oxidative and nitrosative stress-related reactions compared to Hb. Moreover, PEGylation and dialdehyde crosslinking were shown to be feasible procedures for controlling Hr’s molecular weight, oxygen affinity and resistance to autoxidation. The extent to which such modifications may overcome extravasation and antigenicity barriers remain to be determined.

In short, it is apparently no great thing to chemically modify hemerythrin and alter its oxygen binding / releasing affinity to match what we would need. A great benefit as the OP mentions is intrinsic resistance of hemerythrin to poisoning - not only by CO but also nitrite and other oxidative stressors.

I figured that hemerythrin would be phenomenally antigenic - keyhole limpet hemocyanin is used as a vaccine adjuvant because of its immunogencitiy. From what I can tell that is not a huge issue with hemerythrin. I think that the molecule might be chemically modified and polymerized before putting it in artificial blood.

In sum: if used for artificial blood this could work, as evidenced by a number of labs working in earnest on such products. I am more skeptical about genetic engineering humans to express hemerythrin - that would sidestep antigenicity because of tolerance and one could engineer in a genetically hacked version with appropriate O2 avidity... ok, getting less skeptical.

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  • $\begingroup$ That is, my genetically engineered superhumans can use hemeritrin as an oxygen carrier instead of hemoglobin, and due to this, they really will not be afraid of carbon monoxide (this is exactly what I need purple blood for)? $\endgroup$ Dec 26 '20 at 7:17
  • $\begingroup$ @FrenchThompson - at some point as an author you have to say "Screw it - it works because I say it works!" and forge ahead. For example, any story with faster-than-light travel has made this leap. I say go for it, and good luck. $\endgroup$ Dec 26 '20 at 15:43
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    $\begingroup$ Unfortunately, I cannot do so easily, I am writing a documentary scientifically plausible book about a new, more perfect form of man (like Dougal Disc with his book "man after man", just not about several different types of posthumans, but about one specific kind of superman). $\endgroup$ Dec 26 '20 at 17:46
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    $\begingroup$ @FrenchThompson - why not have both? Your superhumans have a small quantity of circulating hemerythrin as a safety net and can inducetranscription of more if exposed to hemoglobin poisons like CO. There are lots of things bodies can do given need, but do not do all the time. Having this stuff handy would be good. $\endgroup$
    – Willk
    Dec 26 '20 at 18:39
  • $\begingroup$ What shade of purple would this be? Also can I have a layman's explanation for PEGylation and dialdehyde crosslinking? And is this something that an alien creature's body might be able to do naturally? You said this will allow the efficiency of oxygen carrying to be improved to what humans need, correct? And would adding more of this PEGylation and dialdehyde crosslinking make it even more efficient than what humans need? $\endgroup$ Sep 27 '21 at 3:46

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