We report that long-chain poly-L-glutamine forms cation-selective channels when incorporated into artificial planar lipid bilayer membranes. The channel was permeable to alkali cations and H(+) ions and virtually impermeable to anions; the selectivity sequence based on the single-channel conductance was H(+) >> Cs(+) > K(+) > Na(+). The cation channel was characterized by long-lived open states (often lasting for several minutes to tens of minutes) interrupted by brief closings. The appearance of the channel depended critically on the length of polyglutamine chains; ion channels were observed with 40-residue stretches, whereas no significant conductance changes were detected with 29-residue tracts. The channel-forming threshold length of poly-L-glutamine was thus between 29 and 40 residues. A molecular mechanics calculation suggests a mu-helix (. Biophys. J. 69:1130-1141) as a candidate molecular structure of the channel. The channel-forming nature of long-chain poly-L-glutamine may provide a clue to the elucidation of the pathogenetic mechanism of the polyglutamine diseases, a group of inherited neurodegenerative disorders including Huntington's disease.

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A polymer, polydicyclopentadiene (PDCPD), is hybridized within the pores of activated carbon (AC) that has micropores and mesopores of ∼4 nm. The hybridization is performed via gas-phase adsorption of dicyclopentadiene (DCPD) on AC and subsequent thermal polymerization. It is confirmed from a variety of analytical techniques, such as scanning and transmittance electron microscopies, a nitrogen adsorption− desorption analysis, and electrochemical measurements, that there is little PDCPD on the particle surfaces of AC. The nitrogen adsorption−desorption measurement of the resulting AC/PDCPD hybrids reveals that the micropore and mesopore volumes decrease with the increasing amount of the hybridized PDCPD. Moreover, the electric double-layer capacitance decreases and the diffusion resistance increases with the increasing amount of the hybridized PDCPD. These results cannot be explained by a micropore filling model where micropores are first filled with PDCPD. Our experimental results reveal that PDCPD does not exist as layers covering the pore walls of AC but exists as agglomerates uniformly distributing inside both micropores and mesopores.

The title bis(imidazol-4-yl)porphyrin 1 gave supramolecular assemblies through hydrogen bonding; efficient excited energy transfer followed by electron transfer to quenchers has been observed in toluene.

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