Warden J T
Biochim Biophys Acta. 1976 Jul 9;440(1):89-97. doi: 10.1016/0005-2728(76)90115-8.
A 300 mus decay component of ESR Signal I (P-700+) in chloroplasts is observed following a 10 mus actinic xenon flash. This transient is inhibited by treatments which block electron transfer from Photosystem II to Photosystem I (e.g. 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), KCN and HgCl2). The fast transient reduction of P-700+ can be restored in the case of DCMU or DBMIB inhibition by addition of an electron donor couple (2,6-dichlorophenol indophenol (Cl2Ind)/ascorbate) which supplies electrons to cytochrome f. However, this donor couple is inefficient in restoring electron transport in chloroplasts which have been inhibited with the plastocyanin inactivators, KCN and HgCl2. Oxidation-reduction measurements reveal that the fast P-700+ reduction component reflects electron transfer from a component with Em = 375 +/- 10 mV (pH = 7.5). These data suggest the assignment of the 300-mus decay kinetics to electron transfer from cytochrome f (Fe2+) to P-700+, thus confirming the recent observations of Haehnel et al. (Z. Naturforsch. 26b, 1171-1174 (1971)).
用10微秒的氙闪光照射后，观察到叶绿体中ESR信号I（P-700+）有一个300微秒的衰减成分。这种瞬态被阻断从光系统II到光系统I的电子转移的处理所抑制（例如3-(3,4-二氯苯基)-1,1-二甲基脲（DCMU）、2,5-二溴-3-甲基-6-异丙基对苯醌（DBMIB）、KCN和HgCl2）。在DCMU或DBMIB抑制的情况下，通过添加向细胞色素f提供电子的电子供体对（2,6-二氯酚靛酚（Cl2Ind）/抗坏血酸），P-700+的快速瞬态还原可以恢复。然而，这种供体对在恢复被质体蓝素失活剂KCN和HgCl2抑制的叶绿体中的电子传递方面效率不高。氧化还原测量表明，快速的P-700+还原成分反映了来自Em = 375 +/- 10 mV（pH = 7.5）的成分的电子转移。这些数据表明将300微秒的衰减动力学归因于从细胞色素f（Fe2+）到P-700+的电子转移，从而证实了Haehnel等人最近的观察结果（《自然科学杂志》26b，1171 - 1174（1971））。
