1978
DOI: 10.1111/j.1751-1097.1978.tb06986.x
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REEVALUATION OF THE SPECTRAL AND KINETIC PROPERTIES OF HO2 AND O2 FREE RADICALS

Abstract: Abstract— The spectra and molar absorbances of the HO2 and O2‐ free radicals have been redetermined in aqueous formate solutions by pulse and stopped‐flow radiolysis as well as by 60Co gamma‐ray studies. The extinction coefficients at the corresponding maxima and 23°C are 225= 1400 ± 80 M‐1 cm‐1 and 225= 2350 ± 120 M‐1 cm‐1 respectively. Reevaluation of earlier published rate data in terms of the new extinction coefficients yielded the following rate constants for the spontaneous decay of HO2 and O2‐: KHo2+HO2… Show more

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Cited by 476 publications
(190 citation statements)
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“…The calculated molar absorbtivities in these three systems (O~ exclusively, O~ in the presence of 13-LOOH, O~ in the presence of t-BOOH) were very similar (2100, 2060, 1970 M -1 .cm -1 ), yet somewhat lower than the latest value for O~ of 2350 M -1 .cm -1 [12]. A very close coincidence was found for the decay rates at pH 7.0:5.6 X l0 s , 2.4 X 10 s , 7.5 X l0 s , all expressed as M -1 .s -1 .…”
Section: Resultsmentioning
confidence: 85%
See 1 more Smart Citation
“…The calculated molar absorbtivities in these three systems (O~ exclusively, O~ in the presence of 13-LOOH, O~ in the presence of t-BOOH) were very similar (2100, 2060, 1970 M -1 .cm -1 ), yet somewhat lower than the latest value for O~ of 2350 M -1 .cm -1 [12]. A very close coincidence was found for the decay rates at pH 7.0:5.6 X l0 s , 2.4 X 10 s , 7.5 X l0 s , all expressed as M -1 .s -1 .…”
Section: Resultsmentioning
confidence: 85%
“…A very close coincidence was found for the decay rates at pH 7.0:5.6 X l0 s , 2.4 X 10 s , 7.5 X l0 s , all expressed as M -1 .s -1 . This relates to the theoretical value of 4.9 X l0 s M -1 .s -1 for the decay of O~ at this pH value [12]. The plot depicted in riga also contains the transient spectrum of the peroxy radical, obtained from "OH-attack at t-butanol and subsequent O2-attachment [13]:…”
Section: Resultsmentioning
confidence: 99%
“…Samples of SODs for pulse radiolysis were prepared by diluting a concentrated enzyme stock solution in an oxygen-saturated solution containing 10 mM potassium phosphate, pH 5.5-8.2, and 100 mM sodium formate to scavenge hydroxyl radicals. The initial concentration of superoxide radical generated by pulse radiolysis was 40-60 pM, which was estimated using E~~~ = 1925 M-' cm-' [21]. The reaction between SOD and superoxide radicals was followed by monitoring the decay of the superoxide radicals at 270 nm.…”
Section: Methodsmentioning
confidence: 99%
“…(1) One mechanism would be the rapid reaction of protonated and unprotonated states of superoxide, both present at pH 4.75 (Bielski, 1978). Superoxide dismutase was not added routinely, since instability at pH 4 might lead to release of copper into the medium.…”
Section: Experimental Conditionsmentioning
confidence: 99%