RESUMO
The luminescence spectrum of singlet oxygen produced upon excitation at 674nm in the photochemically active photosystem II (PS II) complexes isolated from cyanobacterium Synechocystis sp. PCC 6803 containing different types of chlorophyll, i.e., monovinyl (wild-type) or divinyl (genetically modified) chlorophyll a. The yield of singlet oxygen, estimated using methylene blue as the standard, from the divinyl-chlorophyll PS II complex was more than five times greater than that from the monovinyl-chlorophyll PS II complex. These results are consistent with the observed difference in the sensitivity towards high intensity of light between the two cyanobacterial strains. The yield of singlet oxygen appeared to increase with the level of triplet chlorophyll, in the divinyl-chlorophyll PS II complex. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.