Applications 8-Turns/Strands

Large portions of most protein structures can be described as stretches of secondary structure (helices or /3 strands) joined by turns, which provide direction change and offset between sequence-adjacent pieces of secondary structure. Tight turns work well as a-a and a-fi joints, but their neatest application is at a hairpin connection... 

The advent of the polymerase chain reaction (PCR) was a major turning point in the history of analytical techniques for biomolecules. Since the first publication of the method in 1985, the exponential signal amplification power of PCR was mirrored by an almost similar exponential increase of applications [1-4]. Using a simple and effective signal amplification by repetitive cyclic duplication of a template nucleic acid strand, the signal-enhancing... 

Table 10.1 summarizes neural network applications for protein structure prediction. Protein secondary structure prediction is often used as the first step toward understanding and predicting tertiary structure because secondary structure elements constitute the building blocks of the folding units. An estimated 90% or so of the residues in most proteins are involved in three classes of secondary structures, the a-helices, p-strands or reverse turns. Related to the secondary structure prediction are also the prediction of solvent accessibility, transmembrane helices, and secondary structure content (10.2). Neural networks have also been applied to protein tertiary structure prediction, such as the prediction of the backbones or side-chain packing, and to structural class prediction (10.3). 

There is increasing interest in the development of foldamers or polymeric structures that can adopt organised secondary structures like those of proteins, nucleic acids and some polysaccharides [42]. Sugar amino acid-based foldamer research has so far been primarily concerned with synthesis of polymers with secondary sfructural features. Such foldamers may find application as scaffolds for peptidomimetic development if they adopt turn, helical and strand sfructures observed for peptides or if derivatives can act as ligands for peptide receptors ... 

To be successful in these applications, it is important that materials can self-assemble into precisely defined structures. Peptide polymers have many advantages over conventional synthetic polymers since they are able to hierarchically assemble into stable ordered conformations [4]. Depending on the amino acid side chain substituents, polypeptides are able to adopt a multitude of conformationally stable regular secondary structures (helices, sheets, turns), tertiary structures (e.g. the /J-slrand-helix-/J-strand unit found in /1-barrels), and quaternary assembhes (e.g. collagen microfibrils) [4], The synthesis of polypeptides that can assemble into non-natural structures is an attractive challenge for polymer chemists. 

This reaction is recreated in the application of chemistry to cuisine, when adventurous, science-minded chefs cook with spherification. They turn practically any liquid, from green tea to apple juice, into small spheres that burst on the tongue like caviar. The secret is to mix calcium with an oxidized sugar strand like alginate. The... 

The immune system is connected with HA [91-94], Hyaluronan is included into drugs used for the complex treatment of immunodeficient conditions associated with viral diseases. At the molecular level, the mechanism of action of the biopolymer is connected with the blocking of several molecular inflammation factors [93]. On the one hand hyaluronan activates inferonogenesis but on the other it increases action of the interferon inductor (e.g. double-stranded RNA) [91,92]. Interferon is produced mainly by the activated monocytes and T-cells of the immune system. The interleukins-2 and -5 (IL-2, IK-5) play a major role in the activation of T-cells that, in turn, activate synthesis of hyaluronan by endothelial capillary cells. Then hyaluronan stimulates synthesis of CD44 receptors, which is the key event for the activation of the lymphocytes and monocytes [93]. HA is used alone or in combination with interferon to slow down the development of the infection by the virus herpes simplex by application on the infected epithelium [61]. The obvious antimicrobial action of HA can be achieved by its cross-linking with hydrophilic polymers, which are capable of accelerated penetration through cell membranes or intercellular gaps [61]. 

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