‘Low-waves>’ in chlorophyll fluorescence kinetics indicate deprivation of bicarbonate*
‘Low-waves>’ in chlorophyll fluorescence kinetics indicate deprivation of bicarbonate*
复制标题
叶绿素荧光动力学中的“低波>”表明碳酸氢盐的缺乏*
作者：
M. Xyländer;C. Hagen
在绿藻雨生红球藻中观察到，在施加饱和光脉冲后，叶绿素荧光产量短暂可逆降低（所谓的低波），同时 P700 氧化水平短时增强。该现象发生在弱酸性条件下荧光诱导动力学的稳态时间区域，并被碳酸氢盐消除。低波表达后不久，光合析氧速率下降，非光化学叶绿素荧光猝灭成分增加。非光化学叶绿素荧光猝灭成分的增强对尼日利亚菌素敏感，表明其依赖于跨类囊体质子梯度。另一方面，解耦器并未消除低波的形成。只有当额外施加碳酸氢盐时，每次饱和闪光后荧光产量的可逆短期下降才被消除。二甲基-4-亚硝基苯胺作为光系统 I 的人工电子受体并没有限制荧光的短暂下降。然而，甲酸盐作为光系统 II 中碳酸氢盐结合的竞争性抑制剂，诱导低波形成。因此，我们的结果表明，叶绿素荧光动力学中的低波表明光系统 II 反应中心碳酸氢根的缺失。
A brief reversible lowering of chlorophyll fluorescence yield (so called low-waves) immediately after application of a saturating light pulse in parallel with a short-time enhancement of the P700 oxidation level was observed in the green alga Haematococcus pluvialis. The phenomenon occurred in the steady-state time region of fluorescence induction kinetics under mild acidic conditions, and was eliminated by bicarbonate. Shortly after expression of low-waves, the photosynthetic oxygen evolution rate decreased and the non-photochemical chlorophyll fluorescence quenching component increased. The enhancement of the non-photochemical chlorophyll fluorescence quenching component was nigericin-sensitive indicating its dependence on the transthylakoid proton gradient. On the other hand, the formation of low-waves was not removed by the uncoupler. Only when bicarbonate was applied additionally, the reversible short-term decrease in fluorescence yield following each saturating light flash was abolished. Dimethyl-4-nitroso-aniline as an artificial electron acceptor of Photosystem I did not limit the brief drops in fluorescence. However, formate as a competitive inhibitor of bicarbonate binding in Photosystem II induced low-wave formation. Therefore, our results suggest that low-waves in chlorophyll fluorescence kinetics indicate deprivation of bicarbonate in the reaction centre of Photosystem II.