# What would happen if we had a different kind of metal in our bloodstream? [closed]

It is a common fact that we have iron in our blood. But what if we had something different in its place? Like instead of iron what if it was copper, or silver, or what if we had gold in our blood stream instead? Theoretically, what would that do?

## closed as too broad by andselisk♦, Tyberius, Mithoron, Zhe, user55119Jan 24 at 20:54

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• If we would use copper to transport oxygen in the blood, we would be more closely related to horseshoe crabs. – Karsten Theis Jan 24 at 19:01
• Iron in blood is a part of heme group in haemoglobin. Heme is a complex molecule with a porphyrin ring attached to a iron center. Several other such molecules with similar structures are also there, Chlorophyll a has a similar structure with Magnesium at the centre of the Porphyrin ring. Researching on chlorophyll a will give you an idea. – Soura Jan 24 at 19:03
• Instead of one Fe(II) atom like in our heme, the carrier hemocyanin in horseshoe crabs has two bound copper ions to bind to a single dioxygen. – Karsten Theis Jan 24 at 19:07
• The whole biological system of a human is finely tuned. You can't just willy-nilly substitute some other metal for iron in hemoglobin. – MaxW Jan 24 at 19:08
• Assuming that you could construct a recombinant protein that was not rejected by the immune system, and used some metal other than iron in its oxygen-binding cofactor, it makes for an interesting if bizarre question. Afaik release of oxygen is passive (ie does not require another protein, even if it's complex) so if you tuned the protein's $CO_2$ and oxygen binding constants just right, why well, I don't know, it might just work. Question is, why don't we have a copper-loaded oxygen carrier? Just because? – Buck Thorn Jan 24 at 20:01