Abstract
Silica mesoporous materials (SMM) have nano-scale pores its inside and adsorb various molecules. We reported the introduction of light-harvesting LH2-membrane protein complex (137 kDa) of photosynthetic purple bacteria into FSM, a type of SMM with rather small inner pores. In this study we introduced the huge trimer of photosystem I (PSI) reaction center complex (1068 kDa), which was purified from a thermophilic cyanobacterium Thermosynechococcus elongatus and has a diameter of 21 nm, into different types of SMM that are different in pore sizes and outer shapes. The PSI adsorbed into these SMM showed high activity to undergo photochemical reaction of chlorophyll and electron transfer, and retained native pigment protein structure as confirmed by the laser spectroscopy. Moreover, adsorption to SMM increased the heat stability of photochemical activity and the protein structure by 10 ~ 15 degree. Most of the SMM-PSI conjugates revealed high activity in the photo-reduction of methyl viologen.
