|
Synthetic ion channels are ''de novo'' chemical compounds that insert into lipid bilayers, form pores, and allow ions to flow from one side to the other. They are man-made analogues of natural ion channels, and are thus also known as artificial ion channels. Compared to biological channels, they usually allow fluxes of similar magnitude but are # minuscule in size (less than 5k Dalton vs. > 100k Dalton), # diverse in molecular architecture, and # may rely on diverse supramolecular interactions to pre-form the active, conducting structures. Synthetic channels, like natural channels, are usually characterized by a combination of single-molecule (e.g., voltage-clamp of planar bilayers〔) and ensemble techniques (flux in vesicles). The study of synthetic ion channels can potentially lead to new single-molecule sensing technologies as well as new therapeutics. ==History== While semi-synthetic ion channels, often based on modified peptidic channels like gramicidin, had been prepared since the 1970s, the first attempt to prepare a synthetic ion channel was made in 1982 using a substituted β-cyclodextrin. Inspired by gramicidin, this molecule was designed to be a barrel-shaped entity spanning a single leaflet of a bilayer membrane, becoming "active" only when two molecules in opposite leaflets come together in an end-to-end fashion. While the compound does induce ion-fluxes in vesicles, the data does not unambiguously show ''channel'' formation (as opposed to other transport mechanisms; see Mechanism). Na+ transport by such channels was first reported by two groups of investigators in 1989–1990.〔V. E. Carmichael, P. J. Dutton, T. M. Fyles, T. D. James, J. A. Swan, M. Zojaji ''Biomimetic ion transport: a functional model of a unimolecular ion channel'' J. Am. Chem. Soc., 1989, 111, 767–769.〕〔A. Nakano, Q. Xie, J. V. Mallen, L. Echegoyen, G. W. Gokel ''Synthesis of a membrane-insertable, sodium cation conducting channel: kinetic analysis by dynamic sodium-23 NMR'' J. Am. Chem. Soc., 1990, 112, 1287–1289.〕〔G. W. Gokel, I. A. Carasel ''Biologically active, synthetic ion transporters'' Chem. Soc. Rev., 2007, 36, 378.〕 With the adoption of voltage clamp technique to synthetic channel research in the early 1990s, researchers were able to observe quantized electrical activities from synthetic molecules, often considered the signature evidence for ion channels.〔 This led to a sustained increase in research activity over the next two decades. In 2009, over 25 peer-reviewed papers were published on the topic, and a series of comprehensive reviews are available.〔〔〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Synthetic ion channels」の詳細全文を読む スポンサード リンク
|