Functionalized salt bridge

It is important to notice that the united-atom simplification cannot be applied to functional hydrogens which are involved in the formation of a hydrogen hond or a salt bridge. This would destroy interactions important for the structural integrity of the protein. Removing the hydrogen at the u-carbon of the peptide backbone is also dangerous, because it prevents racemization of the amino acid. 

Molecular weights of polymers that function as bridging agents between particles are ca 10 —10. Ionic copolymers of acrylamide are the most significant commercially (see Acrylamide POLYMERS). Cationic comonomers include (2-methacryloyloxyethyl)trimethylammonium salts, diethyl aminoethyl methacrylate [105-16-8], and dimethyldiallylammonium chloride [7398-69-8], anionic comonomers include acryUc acid [79-10-7] and its salts. Both types of polyacrylamides, but especially the anionic, can be more effective in the presence of alum (10,11). Polyetbylenimine and vinylpyridine polymers, eg, po1y(1,2-dimethy1-5-viny1pyridiniiim methyl sulfa te) [27056-62-8] are effective but are used less frequentiy. 

The amino acid sequence of our first aPNA (which we termed backbone 1 or bl) was designed based on this amphipathic hehx sequence (Fig. 5.3 B). Specifically, this aPNA backbone included hydrophobic amino acids (Ala and Aib), internal salt bridges (Glu-(aa)3-Lys-(aa)3-Glu), a macrodipole (Asp-(aa)i5-Lys), and an N-ace-tyl cap to favor a-helix formation. The C-termini of these aPNA modules end in a carboxamide function to preclude any potential intramolecular end effects. Each aPNA module incorporates five nucleobases for Watson-Crick base pairing to a target nucleic acid sequence. 

Table 7.13 Values of junction potential in aqueous cells as a function of the concentration of inert KC1 within a salt bridge...

NAl/3 Val Val or Gly Ser Ac-Ala Ac-Ala In human and many other vertebrate deoxy-Hbs, the a-amino groups bind either organic phosphate or carbamino CO2, which in turn forms a salt bridge with Lys 82 of the same p chain in crocodile Hb, blocking of a-NHs or Pro in position 2 inhibits these functions... 

The functionalization of folded motifs is based on an understanding of secondary and tertiary structures (Fig. 2) and must take into account the relative positions of the residues, their rotamer populations and possible interactions with residues that do not form part of the site. For example, glutamic acid in position i has a strong propensity for salt-bridge formation, and thus reduced reactivity, if there is a Lys residue available i-4 in the sequence, but the probabihty is much less if the base is i-3 [60]. Fortunately, there is a wealth of structural information on the structural properties of the common amino acids from studies of natural proteins that provides considerable support for the design of new proteins. The naturally occurring amino acids have so far been used to construct reactive sites for catalysis [11-13], metal- and heme-binding sites [14,15,19,21,22] and for the site-selective functionalization of folded proteins [24,25]. 

What is the function of a salt bridge in a galvanic cell ... 

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