The temperature stability of electron transfer to the artificial electron acceptor 2,6-dichlorophenolindophenol in preparations of native photosystem II and photosystem II without the calcium cation in an oxygen-evolving complex was studied. The thermal stability of the processes of oxygen evolution and electron transfer from the oxygen-evolving complex to 2,6-dichlorophenolindophenol in photosystem II were significantly different: the reduction of 2,6-dichlorophenolindophenol was more resistant to temperature than oxygen evolution. The reaction of 2,6-dichlorophenolindophenol reduction in the Ca²⁺-depleted preparations of photosystem II was less resistant to heating than in the preparations of native photosystem II. The thermal inactivation of the photosystem II in the Ca²⁺-depleted membrane preparations was inhibited by cytochrome c at a concentration of 50 cytochrome c molecules per a photosystem II reaction center. The activity of this preparation (the rate of the 2,6-dichlorophenolindophenol reduction) increased by 19%, approaching the activity of the native photosystem II. The protective effect of cytochrome c appears to be determined by its protein nature, rather than its redox activity, since an equal protective effect was observed upon the addition of albumin at a similar concentration. Almost complete inactivation of the 2,6-dichlorophenolindophenol reduction reaction in the native and Ca²⁺-depleted preparations of photosystem II was observed at the same temperature (50°C). According to the EPR data, photosystem II in the Ca²⁺-depleted preparation after incubation at this temperature lacked a manganese cluster, while a peripheral protein of 33 kDa was present.

研究了在生氧体系中，天然光系统Ⅱ和不含钙阳离子的光系统Ⅱ中电子向人工电子受体2，6-二氯苯酚吲哚酚的转移的温度稳定性。在光系统II中，析氧过程以及电子从析氧复合物向2,6-二氯苯酚吲哚酚的电子转移过程的热稳定性存在显着差异：2,6-二氯苯酚吲哚酚的还原性比析氧性更耐温度。缺少Ca ²⁺的光系统II制剂中2,6-二氯苯酚吲哚酚还原的反应比天然光系统II的耐热性低。Ca ^2+中光系统II的热失活每个光系统II反应中心，在50种细胞色素c分子的浓度下，细胞色素c抑制了贫化的膜制剂。该制剂的活性（2，6-二氯苯酚吲哚酚的还原率）增加了19％，接近天然光系统II的活性。细胞色素c的保护作用似乎是由其蛋白质性质决定的，而不是由其氧化还原活性决定的，因为在加入相似浓度的白蛋白时，观察到了相同的保护作用。天然和Ca ²⁺中的2,6-二氯苯酚吲哚还原反应几乎完全失活在相同温度（50°C）下观察到光系统II的耗竭制剂。根据EPR数据，在此温度下孵育后，Ca ²⁺耗尽的制剂中的光系统II缺乏锰簇，而存在33 kDa的外周蛋白。