Longatte G, Rappaport F, Wollman F-A, Guille-Collignon M, Lemaître F
Ecole normale supérieure, PSL Research University, UPMC Univ Paris 06, CNRS, Département de Chimie, PASTEUR, 24, rue Lhomond, 75005 Paris, France.
Photochem Photobiol Sci. 2016 Aug 4;15(8):969-79. doi: 10.1039/c6pp00076b. Epub 2016 Jul 14.
Plants or algae take many benefits from oxygenic photosynthesis by converting solar energy into chemical energy through the synthesis of carbohydrates from carbon dioxide and water. However, the overall yield of this process is rather low (about 4% of the total energy available from sunlight is converted into chemical energy). This is the principal reason why recently many studies have been devoted to extraction of photosynthetic electrons in order to produce a sustainable electric current. Practically, the electron transfer occurs between the photosynthetic organism and an electrode and can be assisted by an exogenous mediator, mainly a quinone. In this regard, we recently reported on a method involving fluorescence measurements to estimate the ability of different quinones to extract photosynthetic electrons from a mutant of Chlamydomonas reinhardtii. In the present work, we used the same kind of methodology to establish a zone diagram for predicting the most suitable experimental conditions to extract photoelectrons from intact algae (quinone concentration and light intensity) as a function of the purpose of the study. This will provide further insights into the extraction mechanism of photosynthetic electrons using exogenous quinones. Indeed fluorescence measurements allowed us to model the capacity of photosynthetic algae to donate electrons to an exogenous quinone by considering a numerical parameter called "open center ratio" which is related to the Photosystem II acceptor redox state. Then, using it as a proxy for investigating the extraction of photosynthetic electrons by means of an exogenous quinone, 2,6-DCBQ, we suggested an extraction mechanism that was globally found consistent with the experimentally extracted parameters.
植物或藻类通过将太阳能转化为化学能，利用二氧化碳和水合成碳水化合物，从有氧光合作用中获得诸多益处。然而，这一过程的总体产率相当低（大约只有可利用太阳光总能量的4%转化为化学能）。这就是近期许多研究致力于提取光合电子以产生可持续电流的主要原因。实际上，电子转移发生在光合生物与电极之间，并且可以由外源媒介物（主要是醌）来辅助。在这方面，我们最近报道了一种涉及荧光测量的方法，用于评估不同醌从莱茵衣藻突变体中提取光合电子的能力。在本工作中，我们采用同样的方法建立了一个区域图，以预测从完整藻类中提取光电子的最合适实验条件（醌浓度和光强），该条件是研究目的的函数。这将为使用外源醌提取光合电子的机制提供进一步的见解。实际上，荧光测量使我们能够通过考虑一个称为“开放中心比率”的数值参数来模拟光合藻类向外源醌提供电子的能力，该参数与光系统II受体的氧化还原状态有关。然后，将其用作研究通过外源醌2,6 - 二氯苯醌提取光合电子的代理，我们提出了一种提取机制，总体上发现该机制与实验提取的参数一致。
