Backbone linkage

In an oligonucleotide having n backbone linkages, this gives rise to 2 isomers that vary in their mechanism of action, cellular transport, as well as pharmacokinetics (53). Some of the most frequently encountered backbone modifications are Hsted in Table 1. 

Figure 2.3 Fragment of polypeptide chain backbone illustrating rigid peptide bonds and the intervening N—Ca and Ca—C backbone linkages, which are free to rotate...

Klebsiella K9 has a particularly intriguing backbone linkage geometry. Tts chemical structure, established by Lindberg et al (21), is given in Figure 26. There are three ot-L-rhamnose residues in its backbone, two linked 1, 3 and one linked 1,2. 

Lysine also may form complexes with anionic ligands and thereby increase Am values. In addition, lysine may have an unfavorable effect on protein structure. Because it has a considerable hydrophobic moment, it may interact with hydrophobic sites on the protein, leading to perturbation of structure. Compatible solutes lack a propensity for interacting with peptide backbone linkages or amino acid side-chains, as discussed later. 

The next question to be addressed carries the mechanistic analysis one step further by asking what components of proteins—the side-chains or the peptide backbone linkages—are responsible for solute effects on structure. The answer to this question, which comes from studies... 

The role of the novolac resin is not as minor as it may seem as a base-soluble binder. While the aromatic nature of the resin provides high dry etch resistance, the novolac structures and properties such as the ratio of o-cresol to m-cresol, the ratio of ortho to para backbone linkages, the molecular weight, and molecular weight distribution all affect the dissolution behavior, thermal flow resistance, and lithographic performance. The optimization of the novolac and diazonaphthoquinone properties in conjunction with the improvement of the i-line step-and-repeat exposure tools has pushed the resolution limit of photolithography to a sub-0.5-pm regime [4]. 

Chemical structure of polymers constituting the blend determines its solvent resistance. The polymers, having the backbone linkages involving oxygen, sulfur, and silicone exhibited enhanced chemical and solvent resistance. Thus, enhanced chemical and solvent resistance has been reported for polymer blends that comprise polymers with ... 

Backbone linkage, however, is again able to hold the two sulfurs together and may, in fact, render these processes reversible. A particularly nice example for this is the reduced form of lipoic acid where not only the anion, Lip(S/.S) , (as mentioned before) but also the protonated form, Lip(S. . S,H), are relatively long-lived and unambiguously distinguishable through their different optical absorptions.67 The same considerations apply for the one-electron oxidation product of dithiothreitol.61... 

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