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I have a question that came up in my research (neurobiology), maybe someone can help me out! I read that neuromelanin, which is found in certain brain structures, can chelate iron and protect cells from the toxicity of iron. I also read that chelation means "incorporation of a mineral ion or cation into a complex ring structure" and I know chelation is used to remove iron e.g. in case of overload. However what I don't understand is if chelation will "degrade" the iron molecule (I'm not familiar with the right terminology, sorry!) or if it will just "contain" it but the iron is still intact. The reason why I'm asking is because there is this notion of iron influencing MRI signal in certain regions that contain neuromelanin which binds/chelates iron, but at the same time chelation seems to mean removal. So I'm wondering if chelated iron still has the same properties as "free" iron. Thank you in advance!

"Neuromelanin pigment is able to accumulate different metals, mainly iron. Neuromelanin seems to be the most effective system for scavenging iron, which results in a long-term immobilisation of iron inside neurons." (Ward et al., 2014, The role of iron in brain ageing and neurodegenerative disorders)

"Low Iron in LC Neurons Is Chelated by NM. NM is a strong chelator of heavy metals because of the presence of catechol groups in its structure (31). NM has strong chelating ability for iron, which provides another important mechanism of protection from iron mobilization and the consequent toxicity." (Zecca et al., 2004, The role of iron and copper molecules in the neuronal vulnerability of locus coeruleus and substantia nigra during aging)

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    $\begingroup$ It would be helpful to readers if you put those citations (or references) in your question. $\endgroup$
    – Mathew Mahindaratne
    Mar 25, 2022 at 18:29
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    $\begingroup$ Thank you for the tip, I added a few! @MathewMahindaratne $\endgroup$
    – RBG
    Mar 25, 2022 at 19:03
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    $\begingroup$ Iron is an element. It can be bound in a molecule, e.g., to neuromelanin, or to another chemical, e.g., to ethylenediaminetetraacetic acid (EDTA) or to "NM" (which needs to be defined). What "NM' (or EDTA) do to living organisms is another question, and whether these chelate other vital metals, such as calcium, yet another. BTW, the description seems to border on pseudo-medicine. Chelation is useful for heavy metal poisoning, and has been used to treat those who ingested plutonium, with mixed results. $\endgroup$
    – DrMoishe Pippik
    Mar 25, 2022 at 20:16
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    $\begingroup$ Well, if you used a chelator like EDTA, it would chelate metal ions and later be removed with urine, I guess. This neuromelanin stays where it is along with whatever it chelates, afaict. $\endgroup$
    – Mithoron
    Mar 25, 2022 at 23:02

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if chelation will "degrade" the iron molecule … or if it will just "contain" it but the iron is still intact.

Iron is an element. That means that short of nuclear reactions, it is indestructible and will always remain as iron. It can't degrade.

In chelation, other elements react and combine with the iron to produce a larger, more complicated molecule that contains the iron atom in its interior, where it can no longer be seen (chemically). As far as the body is concerned, it no longer exists.

With an appropriate choice of chelator though, the resulting molecule will be one that the body will recognize as unwanted and will dispose of it, typically by filtering it out of the blood through the kidneys and mixing it into the urine.

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  • $\begingroup$ Chelation is an operation where a chemical substance is surrounding entirely a metal atom like $\ce{Fe}$. This means that this atom cannot interfere any more with any other components of the liquid in which it is dissolved. These components (proteins, enzymes, etc.) will not be puzzled or modified by the metal atom which is chelated. It looks as if the metallic atom has been removed from the solution. $\endgroup$
    – Maurice
    Mar 26, 2022 at 12:47
  • $\begingroup$ @Maurice, thanks. I've updated accordingly. $\endgroup$
    – Ray Butterworth
    Mar 26, 2022 at 13:46

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