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Ascorbate Reacts with Singlet Oxygen to Produce Hydrogen Peroxide
Author(s) -
Kramarenko Galina G.,
Hummel Stephen G.,
Martin Sean M.,
Buettner Garry R.
Publication year - 2006
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2006.tb09823.x
Subject(s) - singlet oxygen , chemistry , hydrogen peroxide , photochemistry , stoichiometry , oxygen , electrophile , singlet state , peroxide , reactive oxygen species , rose bengal , catalysis , organic chemistry , excited state , biochemistry , physics , nuclear physics
Singlet oxygen is a highly reactive electrophilic species that reacts rapidly with electron‐rich moieties, such as the double bonds of lipids, thiols, and ascorbate (AscH ‐ ). The reaction of ascorbate with singlet oxygen is rapid ( k = 3 × 10 8 M ‐1 s ‐1 ). Here we have investigated the stoichiometry of this reaction. Using electrodes to make simultaneous, real‐time measurements of oxygen and hydrogen peroxide concentrations, we have investigated the products of this reaction. We have demonstrated that hydrogen peroxide is a product of this reaction. The stoichiometry for the reactants of the reaction (1 1 O 2 + 1A sc H ‐ 1H 2 O 2 + 1dehydroascorbic) is 1:l. The formation of H 2 O 2 results in a very different oxidant that has a longer lifetime and much greater diffusion distance. Thus, locally produced singlet oxygen with a half‐life of 1 ns to 1 μs in a biological setting is changed to an oxidant that has a much longer lifetime and thus can diffuse to distant targets to initiate biological oxidations.