Hydraphile channels

Murray, C. L. Shabany, H. Gokel, G. W., (2000) The central relay unit in hydraphile channels as a model for the water-and-ion capsule of channel proteins Chem. Commun. 2371-2372. 

An example of such a synthetic mimic is the hydraphile channel system developed by Gokel. The system is based on the 4,13-diaza-18-crown-6 macrocycle 3 (Fig. 2), with an inner crown ether believed to be embedded in the... 

Figure 12.14 Schematic diagram of the hydraphile family of ion channel mimics.

Another way to assess ion channel conductance is to use artificial phospholipid vesicles (liposomes) as cell models. These structures (described in more detail in the next chapter) are commonly used to transport vaccines, drugs, enzymes, or other substances to target cells or organs. The vesicles, which are several hundred nanometres in diameter, do not suffer from interference from residual natural ion channel peptides or ionophores, unlike purified natural cells. A liposome model was used to test the ion transport behaviour of the redox-active hydraphile 12.36. The compound transports Na+ and the process can also be monitored using 23Na NMR spectroscopy.26 The presence of the ferrocene-derived group in the central relay allows the ion transport to be redox-controlled - oxidation to ferrocinium completely prevents Na+ transport for electrostatic reasons. Some representative data from a planar bilayer measurement is shown for hydraphile 12.36 in Figure 12.16. 

Fig. 5.15 Transmembrane channels formed by crown ethers a single filter chundle approach [45] (left) and multifilter hydraphile [46] (right)...

Gokel GW (2000) Hydraphiles design, synthesis and analysis of a family of synthetic, cationconducting channels. Chem Commun 1-9... 

A fluorescent derivative was prepared and it was demonstrated by fluorescence microscopy that the hydraphiles insert in the phospholipid bilayers of the bacterium Escherichia coli <2002JA9022>. The channels are symmetrical and therefore nonrectifying. As such, they permit ions to pass readily in both directions through the organism s outer (plasma) membrane. This makes the hydraphiles toxic to bacteria because the channels permit internal and external ion asymmetry to be disrupted <20050BC1647, 2005OBC3544, 2005CC89>. 

Figure 11 (a) Hydraphile model channel 21 and (b) cartoon representation of hydraphile mode of action. 

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