Backbone channels

Foam bubbles that move in the largest backbone channels are coupled together through lamellae and lenses. They parade in series as trains. Individual bubbles comprising these trains are relentlessly destroyed and recreated, so that the train is in a constant state of rearrangement. Regardless of whether bubbles are generated externally or in situ, they are... 

Fig. 3. (a) Chemical stmcture of a synthetic cycHc peptide composed of an alternating sequence of D- and L-amino acids. The side chains of the amino acids have been chosen such that the peripheral functional groups of the dat rings are hydrophobic and allow insertion into Hpid bilayers, (b) Proposed stmcture of a self-assembled transmembrane pore comprised of hydrogen bonded cycHc peptides. The channel is stabilized by hydrogen bonds between the peptide backbones of the individual molecules. These synthetic pores have been demonstrated to form ion channels in Hpid bilayers (71). 

Fig. 15. Drug binding sites associated with the GABA receptor—channel complex where (— -) represents the carbon backbone of GABA agonists.

Fig. 2. Agents controlling the opening of Cl -channels. The structural formula, the name, the respeetive Cl -channel, and an appropriate reference are provided. (A) Note the similarity of GABA, taurine, and P-alanine. Note also that DPC and its analogues such as NPPB contain a -alanine backbone. (B) The structure of torasemide comes close to both DPC and furosemide or buraetanide. It blocks the Na ZCPK" -cotransporter with very high affinity and with lesser affinity also the TAL-Cl -channel. Note that IAA-94 is related to phenoxyaeetic acids (e.g., ethacrynic acid). Amidine is related to IAA-94 but it has a positive net charge. Amidine as well as IAA-94 block the ICOR channel at around lO mol/1 [63].

More ion channels are related to the Na Ca, and ly, families 108 There are many other kinds of ion channels with different structural backbones and topologies 108... 

The rational synthesis of peptide-based nanotubes by self-assembling of polypeptides into a supramolecular structure was demonstrated. This self-organization leads to peptide nanotubes, having channels of 0.8 nm in diameter and a few hundred nanometer long (68). The connectivity of the proteins in these nanotubes is provided by weak bonds, like hydrogen bonds. These structures benefit from the relative flexibility of the protein backbone, which does not exist in nanotubes of covalently bonded inorganic compounds. 

Tails can be based on organic and silicon organic backbones. Four types of tails play a role, depending on the desired properties. (1) Nonreactive tails. (2) Tails that can undergo an isomerization after insertion under the influence of irradiation, heat, or a sufficiently small reactive. (3) Reactive tails that can bind to molecules inside of the channels. (4) Luminescent tails, that have the advantage of being protected by the zeolite framework. 

The simple water charmel models can explain the ionomer peak and the small-angle upturn in the scattering data of fhe unoriented samples as well as of the oriented films. Interestingly, the helical structure of backbone segments is responsible for fhe sfabilify of fhe long cylindrical charmels. The self-diffusion behavior of wafer and protons in Nation is well described by the water channel model. The existence of parallel wide channels af high wafer uptake favors large hydrodynamic confributions to electro-osmotic water transport and hydraulic permeation. 

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