叶绿体中光系统II和光系统I之间的能量转移。
Energy transfer between photosystem II and photosystem I in chloroplasts.
作者信息
Butler W L, Kitajima M
出版信息
Biochim Biophys Acta. 1975 Jul 8;396(1):72-85. doi: 10.1016/0005-2728(75)90190-5.
A model for the photochemical apparatus of photosynthesis is presented which accounts for the fluorescence properties of Photosystem II and Photosystem I as well as energy transfer between the two photosystems. The model was tested by measuring at - 196 degrees C fluorescence induction curves at 690 and 730 nm in the absence and presence of 5mMMgCl2 which presumably changes the distrubution of excitation energy between the two photosystems. The equations describing the fluorescence properties involve terms for the distribution of absorbed quanta, alpha, being the fraction distributed to Photosystem I, and beta, the fraction to Photosystem II to Photosystem I, KT(II yields I). The data, analyzed within the context of the model, permit a direct comparison of alpha and kt(II yields I) in the absence (minus) and presence (+) of Mg-2+ :alpha minus/alpha-+ equals 1.2 and k-minus t)II yields I)/K-+T(II yields I) equal to 1.9. If the criterion that alpha + beta equal to 1 is applied absolute values can be calculated: in the presence of Mg-2+, alpha-+ equal to 0.27 and the yield of energy transfer, phi-+ t(II yields I) varied the presence of Mg-2+, alpha-+ equal to 0.27 and the yield of energy transfer, phi-+ t(II yields I) varied from 0.065 when the Photosystem II reaction centers were all open to 0.23 when they were closed. In the absence of Mg-2+, alpha-minus equal to 0.32 and phi t(II yields I) varied from 0.12 to 0.28. The data were also analyzed assuming that two types of energy transfer could be distinguished; a transfer from the light-harvesting chlorophyll of Photosystem II to Photosystem I, kt(II yields I), and a transfer from the reaction centers of Photosystem II to Photosystem I, kt(II yields I). In that case alpha-minus/alpha+ equal to 1.3, k-minus t(II yields I)/k+ t(II yields I)equal to 1.3 and k-minus t(II yields I) equal to 3.0. It was concluded, however, that both of these types of energy transfer are different manifestations of a single energy transfer process.
本文提出了一种光合作用光化学装置的模型，该模型解释了光系统II和光系统I的荧光特性以及两个光系统之间的能量转移。通过在-196℃下测量有无5mM MgCl₂时690和730nm处的荧光诱导曲线对该模型进行了测试，MgCl₂可能会改变两个光系统之间激发能的分布。描述荧光特性的方程涉及吸收量子分布的项，α为分配给光系统I的分数，β为分配给光系统II到光系统I的分数，KT（II产生I）。在该模型的背景下分析这些数据，可以直接比较有无Mg²⁺时的α和kt（II产生I）：α⁻/α⁺ = 1.2，k⁻t（II产生I）/K⁺T（II产生I） = 1.9。如果应用α + β = 1的标准，则可以计算绝对值：在有Mg²⁺的情况下，α⁺ = 0.27，能量转移产率φ⁺t（II产生I）有所变化，在有Mg²⁺的情况下，α⁺ = 0.27，能量转移产率φ⁺t（II产生I）在光系统II反应中心全部开放时为0.065，在关闭时为0.23。在没有Mg²⁺的情况下，α⁻ = 0.32，φt（II产生I）在0.12至0.28之间变化。还假设可以区分两种类型的能量转移来分析数据；一种是从光系统II的捕光叶绿素到光系统I的转移，kt（II产生I），另一种是从光系统II的反应中心到光系统I的转移，kt（II产生I）。在这种情况下，α⁻/α⁺ = 1.3，k⁻t（II产生I）/k⁺t（II产生I） = 1.3，k⁻t（II产生I） = 3.0。然而，得出的结论是，这两种类型的能量转移都是单一能量转移过程的不同表现形式。
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