Trehalose as a tool for studying the molecular mechanisms of electron transfer in photosynthetic systems

In this review, we consider the effects of trehalose on charge transfer processes in three distinct photosynthetic systems under different conditions, namely: (i) the effect of relative hydration of the trehalose glassy matrix on forward and backward electron transfer (ET) in Mn-depleted photosystem (PS) II core complexes; (ii) stabilization of the light-induced voltage in the presence of trehalose in hybrid system, comprising PS I immobilized onto membrane filter (MF) and semiconductors; (iii) the effect of trehalose on the charge transfer reactions in the photosynthetic bacterial chromatophores. The systems significantly differ from each other: in the case of PS II, the protein is surrounded by relatively dry glassy matrix, while PS I is immersed within the MF, and chromatophore vesicles are in aqueous solution. Nevertheless, in all these systems trehalose reveals several common features–confinement of the protein conformational mobility, preventing damage and degradation of the proteins at room temperature and prolonged storage of the photosynthetic systems at high trehalose-water ratio. These observations highlight that trehalose is extremely powerful tool for the study of ET mechanisms in protein complexes. Moreover, significant stabilization of the photosynthetic complexes by trehalose indicates the promising approach in the design of sustainable semisynthetic ecologically safe solar energy converters.