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John Gibbons <jgibbo@ph*.lo*.ac*.uk*> wrote:-
> ... there are two types of O2 poisoning. We may find that the cure for one
> will aggravate the other. A group looking into pulmonary O2 tox (chronic)
> were getting good results by overexpressing superoxide dismutase [in rats]
> to get rid of the oxygen free radicals and reactive oxygen species that are
> in O2. When they tried the same thing [in rats] with acute O2 tox they found
> that the seizures occured sooner (lower ppO2).
It sounds like the seizures may be produced by hydrogen peroxide. In which
case, what happens if you also overexpress the enzyme that gets rid of
hydrogen peroxide?
Electrons in metabolism are mostly handled singly by compounds (e.g.
cytochrome C) that contain iron atoms that change between ferric & ferrous.
e- + O2 + H+ -> HO2 (hydrogen superoxide)
2 HO2 -> HOOH + O2 (by superoxide dismutase)
2 HOOH -> O2 + H2O (and that's got rid of all the dangerous stuff)
There is one case where an oxygen molecule is added directly to an organic
molecule in ordinary biochemistry: there is an enzyme that uses an O2 molecule
as an explosive charge to blast a C6 aromatic ring open when breaking up one
of the amino acids.
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