Answers are grounded in this paper and cite their sources.
The oxidation of 3, 4‐dihydroxyphenylalanine (dopa) photosensitized by hematoporphyrin has been studied by ESR spectroscopy. The nitroxide free radical 2, 2, 6, 6‐tetramethyl‐4‐piperidone‐I‐oxyl (TEMPONE) is shown to be a convenient probe for monitoring oxygen consumption during the reaction. Isotope and azide effects on oxygen consumption suggest that photooxidation in D 2 O proceeds mainly by a singler oxygen mechanism, whereas in H 2 O both singlet oxygen and free radical mechanisms are important. The relative importance of these mechanisms can change as oxygen is consumed during the photoreaction. TEMPONE also can be used as an indicator of the presence of reducing radicals (in this case hematoporphyrin radical anions) in the system, but only at low oxygen levels: in aerated solutions efficient reaction of these radical ions with oxygen is proposed.
No takes yet. Share an insight, caveat, or question.
Reszka et al. (1984) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: