Durrant J R, Hastings G, Joseph D M, Barber J, Porter G, Klug D R
Department of Biology, Imperial College, London, United Kingdom.
Proc Natl Acad Sci U S A. 1992 Dec 1;89(23):11632-6. doi: 10.1073/pnas.89.23.11632.
Photosystem II reaction centers have been studied by femtosecond transient absorption spectroscopy. We demonstrate that it is possible to achieve good photoselectivity between the primary electron donor P680 and the majority of the accessory chlorins. Energy transfer can be observed in both directions between P680 and these accessory chlorins depending on which is initially excited. After excitation of either P680 or the other chlorins, the excitation energy is observed to equilibrate between the majority of these pigments at a rate of 100 +/- 50 fs-1. This energy-transfer equilibration takes place before any electron-transfer reactions and must therefore be taken into account in studies of primary electron-transfer reactions in photosystem II. We also show further evidence that the initially excited P680 excited singlet state is delocalized over at least two chlorins and that this delocalization lasts for at least 200 fs.
通过飞秒瞬态吸收光谱对光系统II反应中心进行了研究。我们证明，在初级电子供体P680和大多数辅助二氢卟吩之间能够实现良好的光选择性。根据最初被激发的是哪一种，在P680和这些辅助二氢卟吩之间可以观察到双向的能量转移。在激发P680或其他二氢卟吩之后，观察到激发能量在大多数这些色素之间以100±50 fs-1的速率达到平衡。这种能量转移平衡在任何电子转移反应之前发生，因此在光系统II初级电子转移反应的研究中必须予以考虑。我们还进一步证明，最初被激发的P680激发单重态至少在两个二氢卟吩上离域，并且这种离域持续至少200 fs。
