Noren G H, Boerner R J, Barry B A
Department of Biochemistry, University of Minnesota, St. Paul 55108.
Biochemistry. 1991 Apr 23;30(16):3943-50. doi: 10.1021/bi00230a020.
The transformable cyanobacterium Synechocystis 6803 has a photosynthetic apparatus that is similar to that of plants. Because of the ease with which this organism can be genetically manipulated and isotopically labeled, Synechocystis has been used extensively in recent studies of electron transfer in the water-splitting complex, photosystem II. Here, we present the first EPR characterization of a highly active oxygen-evolving preparation from this organism. This preparation shows oxygen-evolution activities in the range from 2400-2600 mumol of O2/(mg of chlorophyll.h). We show that this preparation is stable enough for room temperature EPR studies. We then use this assay to show that the lineshapes of the D+ and Z+ tyrosine radicals are identical in this preparation, as has been observed in photosystem II complexes from a wide variety of photosynthetic species. We also present the first multiline EPR spectrum that has been observed from the Synechocystis manganese cluster.
可转化蓝藻集胞藻6803具有与植物相似的光合装置。由于这种生物体易于进行基因操作和同位素标记，集胞藻在最近关于光合系统II水裂解复合物中电子转移的研究中得到了广泛应用。在此，我们展示了对该生物体高活性放氧制剂的首次电子顺磁共振（EPR）表征。该制剂的放氧活性范围为2400 - 2600 μmol O₂/（mg叶绿素·h）。我们表明，这种制剂足够稳定，可用于室温EPR研究。然后我们利用该测定法表明，在这种制剂中，D⁺和Z⁺酪氨酸自由基的线形与在多种光合物种的光合系统II复合物中观察到的相同。我们还展示了首次从集胞藻锰簇观察到的多线EPR谱。
