Harbour J R, Tollin G
Department of Chemistry, University of Arizona, Tucson, Ariz. 85721.
Proc Natl Acad Sci U S A. 1972 Aug;69(8):2066-8. doi: 10.1073/pnas.69.8.2066.
Illumination at low temperatures of ethanol solutions of p-benzoquinone, alone or in the presence of chlorophyll or pheophytin, leads to the reversible formation of radical complexes. Based on g-value determinations and deuterium-substitution effects, the radicals are identified as a semiquinone and an ethoxy radical. In the porphyrin-sensitized system, ternary complexes are produced. Chlorophyll also forms a cation radical upon illumination, whereas pheophytin does not. The generation of this cation radical is independent of the presence of quinone, and proceeds via the chlorophyll singlet state, as opposed to quinone and ethoxy radical production, which involve triplet states. The significance of these reactions to photosynthetic energy conversion is discussed.
在低温下，对苯醌的乙醇溶液单独或在叶绿素或脱镁叶绿素存在的情况下受到光照，会导致自由基复合物的可逆形成。基于g值测定和氘取代效应，这些自由基被鉴定为半醌和乙氧基自由基。在卟啉敏化体系中，会产生三元复合物。叶绿素在光照下也会形成阳离子自由基，而脱镁叶绿素则不会。这种阳离子自由基的产生与醌的存在无关，并且通过叶绿素单重态进行，这与涉及三重态的醌和乙氧基自由基的产生相反。讨论了这些反应对光合能量转换的意义。
