Controlling Material Transport - Ion Channels

The exchange transport mechanism for Na+ and K can be briefly explained as follows. When three Na ions bind to the protein, phosphorylation occurs. 

When a nerve system is excited, Na+ flows into the cell from inside and K+ flows out of the cell through ion channels. These flows obey ion gradients. Active transport occurs upon ATP consumption in order to compensate for these flows and maintain an unbalanced ion distribution between the inside and the outside of the cell. 

As described above, ion channels play an important role in biological activity and they can be mimicked using a supramolecular approach. In this area of research, stable pore structures are formed from artificial molecules that are buried in a lipid bilayer membrane. For example, artificial channel structures have been prepared using specifically designed oligopeptides. 

Some natural ion channels are believed to form amphiphilic a-helix bundles in hydrophobic lipid membranes, where the a-helices assemble with their hydrophilic parts facing each other, resulting in a hydrophilic channel. If artificial peptides that had appropriate combinations of both hydrophobic amino acid residues and hydrophobic amino acid sequences were used, the peptides would self-assemble to form a hydrophilic pathway in the lipid membrane. 

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Controlling Material Transport - Ion Channels Ion channels maintain two different ion compositions outside and inside a cell via active transport. The immobilization of appropriately designed molecules in a lipid bilayer membrane leads to the formation of artificial ion channels. 

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