Allakhverdiev S I, Ahmed A, Tajmir-Riahi H A, Klimov V V, Carpentier R
Centre de recherche en photobiophysique, Université du Québec à Trois-Rivières, Canada.
FEBS Lett. 1994 Feb 14;339(1-2):151-4. doi: 10.1016/0014-5793(94)80404-4.
The structure of the primary electron donor of photosystem II, P680, is still under debate. It is not decided if it is composed of a chlorophyll (Chl) monomer or dimer. In this study, Fourier transform infrared (FTIR) spectroscopy was used to analyze the changes in the vibration modes occurring upon photooxidation of P680 in a Mn-depleted PS II preparation. It is demonstrated that illumination of the above in the presence of artificial electron acceptors results in a light-minus-dark absorbance change typical of the formation of P680+. The light-minus-dark difference FTIR spectrum obtained under similar conditions is characterized by two negative peaks located at 1694 and 1652 or 1626 cm-1 that can be assigned to the 9-keto groups of the P680 Chl, the latter band being indicative of a strongly associated group. These vibrations are shifted to 1714 and 1676 cm-1, respectively, in the positive features of the difference spectrum attributed to P680+. The occurrence of two pairs of bands attributed to 9-keto groups is discussed in terms of P680 being formed of a Chl dimer.
光系统II的初级电子供体P680的结构仍存在争议。其是由叶绿素（Chl）单体还是二聚体组成尚无定论。在本研究中，傅里叶变换红外（FTIR）光谱被用于分析在贫锰PS II制剂中P680光氧化时发生的振动模式变化。结果表明，在人工电子受体存在的情况下照射上述样品会导致出现典型的P680 +形成的光减暗吸光度变化。在类似条件下获得的光减暗差示FTIR光谱的特征是在1694和1652或1626 cm-1处有两个负峰，可归属于P680 Chl的9-酮基，后一个波段表明存在强缔合基团。在归属于P680 +的差示光谱的正特征中，这些振动分别移至1714和1676 cm-1。根据由Chl二聚体形成的P680来讨论归属于9-酮基的两对谱带的出现情况。
