Measurements of the light-induced steady state electric potential generation by photosynthetic pigment-protein complexes

In this minireview, we consider the methods of measurements of the light-induced steady state transmembrane electric potential (& UDelta;& psi;) generation by photosynthetic systems, e.g. photosystem I (PS I). The microelectrode technique and the detection of electrochromic bandshifts of carotenoid pigments are most appropriate for & UDelta;& psi; measurements in situ and in vivo. Direct electrometrical method and & UDelta;& psi; measurements in the photovoltaic system based on membrane filter (MF) sandwiched between semiconductor indium tin oxide electrodes (ITO) are suitable for studies of isolated pigment-protein complexes and small natural vesicles-chromatophores. In the presence of trehalose, ITO|PS I-MF|ITO system allows to keep a steady state level of increment & psi; after 1 h of illumination. According to preliminary experiments, this system is capable of providing steady state light-induced increment & psi; after several months of storage in the dark at room temperature under controlled humidity in the presence of trehalose. The long-term generation of light-induced increment & psi; in relatively simple system may serve as a source of the solar-to-electric energy conversion.

Automated summary

This minireview discusses the methods for measuring the light-induced steady state transmembrane electric potential (ΔΨ) generation in photosynthetic systems, focusing on photosystem I (PS I). The microelectrode technique and the detection of electrochromic bandshifts of carotenoid pigments are suitable for in situ and in vivo ΔΨ measurements. Direct electrometrical methods and measurement of ΔΨ in photovoltaic systems based on membrane filters (MF) are appropriate for studying pigment-protein complexes and natural vesicles-chromatophores. It was found that the ITO|PS I-MF|ITO system, in the presence of trehalose, can maintain a steady state level of ΔΨ increment after prolonged storage.