The light-induced functioning of photosynthetic pigment-protein complex of photosystem II (PSII) is linked to the vectorial translocation of charges across the membrane, which results in the formation of voltage. Direct measurement of the light-induced voltage (∆V) generated by spinach oxygen-evolving PSII core complexes adsorbed onto a Millipore membrane filter (MF) on an indium tin oxide (ITO) electrode under continuous illumination has been performed. PSII was shown to participate in electron transfer from water to the ITO electrode, resulting in ∆V generation. No photovoltage was detected in PSII deprived of the water-oxidizing complex. The maximal and stable photoelectric signal was observed in the presence of disaccharide trehalose and 2,6-dichloro-1,4-benzoquinone, acting as a redox mediator between the primary quinone acceptor Q_A of PSII and electrode surface. Long time preservation of the steady-state photoactivity at room temperature in a simple in design ITO|PSII-MF|ITO system may be related to the retention of water molecules attached to the PSII surface in the presence of trehalose.

光系统 II (PSII) 的光合色素-蛋白质复合物的光诱导功能与电荷跨膜的矢量易位有关，从而导致电压的形成。在连续照明下，直接测量了由菠菜氧演化 PSII 核心复合物吸附在氧化铟锡 (ITO) 电极上的微孔膜过滤器 (MF) 上产生的光诱导电压 (ΔV)。PSII 被证明参与了从水到 ITO 电极的电子转移，从而产生了 ∆V。在没有水氧化复合物的 PSII 中没有检测到光电压。在二糖海藻糖和 2,6-二氯-1,4-苯醌存在下观察到最大和稳定的光电信号，作为初级醌受体 Q 之间的氧化还原介质PSII和电极表面的_A。在设计简单的 ITO|PSII-MF|ITO 系统中，在室温下长时间保持稳态光活性可能与海藻糖存在下附着在 PSII 表面的水分子的保留有关。