Molecular assembly of becteriochlorophills of light-harvesting model plypeptides and its characterization

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It is interesting to note that the light-harvesting (LH) polypeptides of photosynthetic bacteria organize bachteriochlorophyll a ( BChla ) complex according to cooperative interactions between the polypeptide and BChla so that an efficient energy-transfer and electron-transfer processes of porphyrins may occur. In this paper, we now demonstrate molecular assemblies of BChla and its analogue and by using light-havesting polypeptide and synshtetic hydrophobic alpha-helix polypeptides in n-octyl-beta-D-glucopyranoside (OG) micelle to provide an insight into the effect of amino acid residues of the LH polypeptide on formation of the LH complex of photosynthetic bacteria as following.1) The effect of halothane, chloroform and hexanol on reconstituted light-harvesting (LH) polypeptides-bacteriochlorophyll a(BChla) complex from photosynthetic bacteria in n- octyl- beta -D-glucopyranoside (OG) was examined to provide insight into the action of anaesthetics to the membrane protein complex. Halo … More thane has the strongest denaturing effect for both the reconstituted complex and the chromatophore from photosynthetic bacteria. Furthermore, the effect was analyzed by thermodynamics on the stability of the LH-Bchl a complex and the comparison of the denaturing effect was made. The denaturing effect became large in the following order, halothane > chlorohorm >> hexanol.2) We demonstrated molecular assemblies of bacteriochloro-phyll (B Chla) and its analogues by using hydrophobic 1 a-helix polypeptides and 2 a-helix polypeptides with disulfide-linkage. The key to the molecular assembly is a ready availability of examination of the amino acid residue necessary for forming LH1 complex of photosynthetic bacteria by using hydrophobic 2a-helix polypeptides. Spectroscopic properties of bachteriochlorophylls / LH-model polypeptides complex in n-octyl-b-D-glucopyranoside micelle were analogous to those obtained using light-harvesting polypeptides from photosynthetic bacteria especially when 2 a-helix polypeptides were present. Less