Abstract: The lhcⅡ gene from Chlamydomonas reinhardtii was cloned and expressed in Escherichia coli. The LHCⅡrecombinant was prepared using genetic engineering technology, and then reconstructed with chlorophyll a in vitro. The saturation curve of the complex of LHCⅡ/chlorophyll-a was obtained. The free chlorophyll a and the complexs of LHCⅡ/chlorophyll a (at same concentration) were fixed on the TiO2 electrode, and the photoelectric conversion properties of these two materials were compared. One recombinant LHCⅡ bound with 8 chlorophyll a molecules. Under the conditions of AM1.5, light intensity of 100 mW/cm2, shortcut circuit current of LHCⅡ/chlorophyll-a complex is 0.493 mA/cm2, open circuit voltage is 0.491 V, fill-factor is 0.679, and the efficiency is 0.165%. In comparison, shortcut circuit current of free chlorophyll a is 0.596 mA/cm2, open circuit voltage is 0.482 V, and fill-factor is 0.676, efficiency is 0.194%. The recombinant LHCⅡ protein obtained from E. coli BL21 was successfully combined with chlorophyll a in vitro with similar binding activity as its native proteins. The reconstituted pigment-protein complex fulfilled the light harvesting and electron transport functions in a dye-sensitized solar cell system, and showed promising photoelectric properties at lower concentrations. In this study, large-scale preparation of LHCⅡ, the binding activity of recombinant protein LHCⅡ with chlorophyll in vitro, and its application in photoelectric conversion has laid a foundation.

Key words: LHCⅡ, chlorophylls, dye-sensitized solar cells