Pulles M P, Van Gorkom H J, Willemsen J G
Biochim Biophys Acta. 1976 Dec 6;449(3):536-40. doi: 10.1016/0005-2728(76)90162-6.
Absorbance changes are reported associated with Photosystem II and showing a periodicity of two and four as a function of flash number. The absorbance changes showing a periodicity of two were found to occur in the presence of artificial electron donors as well and are presumably caused by the secondary electron acceptor R of Photosystem II. The absorbance difference spectra suggest that R is a plastoquinone molecule, which is reduced to its semiquinone anion after an uneven number of flashes. After an even number of flashes, the semiquinone is reoxidized. The absorbance changes showing a periodicity of four are tentatively ascribed to the charge accumulating donor complex of Photosystem II.
据报道，光吸收变化与光系统II相关，并显示出作为闪光次数函数的二倍和四倍周期性。发现具有二倍周期性的光吸收变化在人工电子供体存在的情况下也会发生，并且可能是由光系统II的次级电子受体R引起的。光吸收差光谱表明R是一种质体醌分子，在奇数闪光后被还原为其半醌阴离子。在偶数闪光后，半醌被再氧化。具有四倍周期性的光吸收变化暂时归因于光系统II的电荷积累供体复合物。
