Talk:Superoxide

This article needs review

This article is not entirely correct and requires review. —The preceding unsigned comment was added by 130.194.13.105 (talk • contribs) .

That's not very helpful. What parts of it are incorrect? —Keenan Pepper 16:34, 26 May 2006 (UTC)

Well, for starters, the anion doesn't decompose into hydrogen peroxide! I've placed a verify tag at the top. --HappyCamper 23:51, 27 May 2006 (UTC)

I revised the first part consulting an authoritative inorganic text, which is also cited. Let me know if problems remain.--Smokefoot 04:00, 11 June 2006 (UTC)

I'm taking a look as well: I know from bitter experience that it can be difficult to correctly describe the chemistry of superoxide. Physchim62 (talk) 11:06, 12 June 2006 (UTC)

The biochemistry and organic chem might be complex, but the basic inorganic chemistry of this diatomic anion is straightforward.--Smokefoot 18:15, 24 June 2006 (UTC) Anyway, what does "verify" mean?

This article seems mostly correct to me. Regarding the relation between superoxide and peroxide, superoxide is converted to hydrogen peroxide by the enzyme superoxide dismutase. This is an important reaction in biology.--Nick Y. 23:58, 24 July 2006 (UTC)

Another problem: the "Lewis electron" graphic is misleading and unhelpful, since it shows a single O-O bond. The superoxide ion is a "radical anion": an oxygen molecule with an extra electron added to a p-p pi antibonding orbital, leaving a bond order of 1.5. . .LinguisticDemographer 11:10, 27 February 2007 (UTC)

I'd also like to see the Lewis electron configuration corrected to include the double bond between the two oxygens. —Preceding unsigned comment added by Mjfim (talk • contribs) 20:56, 27 November 2007 (UTC)

This is poorly written, contains incorrect information, and I think needs to be rewritten before being put back in the article:

Despite being chemically rather benign, superoxide is so toxic that intracellular levels above 1nM are lethal. The biological toxicity of superoxide is not entirely understood, but derives in part from its capacity to inactivate iron-sulfur cluster containing enzymes (which are critical in a wide variety of metabolic pathways), thereby liberating free iron in the cell, which can undergo Fenton chemistry and generate the highly reactive hydroxyl radical. In its HO₂ form (hydroperoxyl radical), superoxide can also initiate lipid peroxidation of polyunsaturated fatty acids. It also reacts with carbonyl compounds and halogenated carbons to create toxic peroxy radicals. Superoxide can also react with nitric oxide (NO) to form ONOO⁻. Superoxide can also form tyrosine peroxides as a result of reaction with enzymes containing tyrosyl radicals (such as ribonucleotide reductase). Superoxide can also oxidize hemoglobin (forming the non-oxygen carrying met-hemoglobin), and possibly other low-potential heme proteins. Finally, superoxide can oxidize low potential thiols. As such, superoxide is one of the main causes of oxidative stress.

--Xris0 (talk) 16:07, 4 May 2009 (UTC)

The section that describes superoxide as being extremely toxic is also inacurate. General consensus is that superoxide itself is not very toxic, but rather it is the metabolites of superoxide that are really toxic -- namely, hydrogen peroxide (formed when SOD activity is insufficient to offset superoxide production), hydroxyl radical (formed by the iron-catalyzed Fenton/Haber Weiss reaction), hypochlorus acid (formed from the reaction of hydrogen peroxide with chloride -- this is one of the key mechanisms underlying the antimicrobial activity of neutrophils, along with proteolytic enzymes), and peroxynitrite (formed by the reaction of hydroxyl radical and nitric oxide). The section in question could definitely do with a rewrite. I'll try to tackle it at some point unless someone else wants to have a go at it. Rhode Island Red (talk) 06:54, 20 August 2009 (UTC)

It is unfortunate that some pages such as this one seem to get abandoned. It is indeed in need of amplification, clarification, and correction. It appears that, if no one claims ownership, a page can languish for quite a long time. The use of Wikipedia has now become so widespread that it often serves to proliferate bad information, or at the very least, uncritical information. The biochemistry of superoxide is very complex. Perhaps it is too much to expect a short and reliable explication from Wikipedia. Anyone to the rescue? Tachyon 01:59, 26 August 2011 (UTC) — Preceding unsigned comment added by Janopus (talk • contribs)

dioxygen is also a diradical

The 201303319 version of the introduction discussed the free radical character of superoxide anion, but did not mention that the parent molecular oxygen (dioxygen) is also a diradical with two unpaired electrons. I altered the text to reveal and clarify that both superoxide and molecular oxygen are radicals Tachyon (talk) 21:44, 19 March 2013 (UTC)

Inconsistency O⁻
₂ or ^•O⁻
₂

Article Reactive oxygen species uses ^•O⁻
₂ and HO^•
₂ for the protonated species. This article uses O⁻
₂ and HO₂· (small radical dot) for the protonated species. Grimes2 (talk) 14:16, 11 June 2016 (UTC) Grimes2 (talk) 14:33, 11 June 2016 (UTC) Grimes2 (talk) 14:40, 11 June 2016 (UTC)

Ultraviolet Radiation Effects

There apparently are effects on the actions of superoxides by ultraviolet radiation. NASA has stated such in relation to its Mars studies. Whether such is the case on Earth is something that should be investigated and reflected in this article on superoxides. Laserray7 (talk) 18:05, 1 September 2017 (UTC)

References

Questions

The article currently says in the intro

Molecular oxygen (dioxygen) is a diradical containing two unpaired electrons,

but later on the article claims that dioxygen's bond has a bond order of 2, which to me would imply that there are no unpaired electrons in O₂.

Further down, the article says

although hydroperoxyl predominates at physiological pHs.

Earlier the article claimed that the superoxide anion predominates. AxelBoldt (talk) 08:41, 29 June 2018 (UTC)

The first statement is fine. O2 is a weirdo (hence life as we know it): it has a double bond and is a diradical. Your second point indeed highlights a contradiction. Thank you for the help.--Smokefoot (talk) 11:23, 29 June 2018 (UTC)

Inappropriate negative connotation in Biology section.

Superoxide has essential regulatory roles in many signaling pathways, and its generation is conserved. It even has been shown to trigger longevity in the right context, so the section emphasizing its role strictly in pathology should be rewritten. Longevity in C-elegans: https://doi.org/10.1371/journal.pbio.1000556 2A00:A041:561:F900:816C:10BE:65ED:65D9 (talk) 21:28, 20 April 2024 (UTC)