The transmembrane light-harvesting (LH) 1 complex in bacterial photosynthetic membranes collects a solar photon energy and transfers it to a reaction center (RC) where a charge separation occurs. The LH1 complex is likely to contain about 16 mers of the subunit complex consisting of two hetro α-helix transmembrane polypeptides and bacteriochlorophyll α (BChl α). However, the handling method and modification of the LH1 complex based on the self-assemble method is not well studied. Thus, the self-assembly of the LH 1 complex or its model complex was studied as follows; The LH1 complexes incorporated into the liposome of the tetraether lipid from Archea were thermostable and the two-dimensional organization of the membrane containing the LH1 complex as proteoliposome was performed. The LB membrane of the LH1 complexes over 10 layers and as Y type were successfully constructed. Further, the modification and the amino acid mutation of the LH polypeptides in the LH1 complex by chemical synthesis indicated that polar amino acids such as Trp residue near C-terminal of the LH 1 polypeptides play an important role on the self-assembly. Interestingly, mesoporphyrin dimers can be reconstituted by using the LH polypeptides, indicating that the π electron system of the porphyrin was successfully assembled and extended analogous to the LH1 complex. These results imply that the LH1 complex and its model complex have several potentials for developing to materials of artificial antenna complex, photo sensitizer, and non-linear optics.

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Owing to a long-standing research on the electrochemical gene sensor or genosensor, especially by the introduction of new strategies of electrochemical nucleic acid detection in recent years, it is now possible to analyze genes with high sensitivity. Detection of a one-base mismatch is of particular importance from a viewpoint of single nucleotide polymorphisms, SNPs. Barton's and our groups developed novel methods of detecting a one-base mismatch which do not rely on a difference in the thermal stability of matched and mismatched duplex DNA. These methods are expected to enable simultaneous analysis of multiple genes with multi-electrodes and are useful for the development of even more sophisticated electrochemical DNA chips. The micro processing technology has been renovating genosensors and it is now possible to immobilize DNA probes in a specific site on such integrated electrodes by the electrochemical method. Electrochemical visualization of ordinary DNA microarrays by means of scanning electrochemical microscopy (SECM) may open a new vista to develop novel electrochemical DNA chips and related systems.

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