HO[sub 2]�: The Forgotten Radical

de Grey, Aubrey D.N.J.
April 2002
DNA & Cell Biology;Apr2002, Vol. 21 Issue 4, p251
Academic Journal
HO[sub 2]�, usually termed either hydroperoxyl radical or perhydroxyl radical, is the protonated form of superoxide; the protonation/deprotonation equilibrium exhibits a pK[sub a] of around 4.8. Consequently, about 0.3% of any superoxide present in the cytosol of a typical cell is in the protonated form. This ratio is rather accurately reflected by the published literature on the two species, as identified by a PubMed search; at the time of writing only 28 articles mention "HO2," "hydroperoxyl" or "perhydroxyl" in their titles, as against 9228 mentioning superoxide. Here it is argued that this correlation is not justifiable: that HO[sub 2]�'s biological and biomedical importance far exceeds the attention it has received. Several key observations of recent years are reviewed that can be explained much more economically when the participation of HO[sub 2]� is postulated. It is suggested that a more widespread appreciation of the possible role of HO[sub 2]� in biological systems would be of considerable benefit to biomedical research.


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