Structural feature incorporation

These natural toxins are heptapeptides produced by cyanobacteria, which are associated with algal blooms. These substances are a hazard to wild and farm animals and sometimes humans who come in contact with contaminated water. There are a number of these toxins, some of which such as microcystin LR are hepatotoxic, causing damage to both hepatocytes and endothelial cells. The toxins have some unusual structural features, incorporating three D-amino acids and two very unusual ones, namely, methyldehydro alanine (Mdha) and amino-methoxy-trimethyl-phenyl-decadi-enoic acid (Adda) (Fig. 7.26). 

These natural toxins are heptapeptides produced by cyanobacteria and have unusual structural features, incorporating three D-amino acids. Microcystin LR is hepatotoxic, as a result of inactivation of protein phosphatases, which leads to breakdown of the cytoskeleton and cell death. 

Leigh, W. J. Zheng, K. /. Am. Chem. Soc. 1991,113,4019 reported evidence for photochemical disrotatory ring opening in one bicyclic system incorporating a cyclobutene ring, but the stereospecificity in such cases seems to depend on the structural features incorporated into the reactants. For a discussion of the relationship of orbital symmetry to the photochemistry of cyclobutene, see Leigh, W. J. Can. ]. Chem. 1993, 71,147. 

These and odier solutions to die problem of eorreedy folding peptides illustrate not only that the location by epitope mapping of antigenic epitopes within a protein s sequence is a prerequisite for the design of synthetic peptide-based vaccines but also that some knowledge of the three dimensional structure of the antigen may be required. In many cases, unless individual epitopes are identified and appropriate structural features incorporated into them, antibody of the correct specificity will not be induced. 

Acid-treated clays were the first catalysts used in catalytic cracking processes, but have been replaced by synthetic amorphous silica-alumina, which is more active and stable. Incorporating zeolites (crystalline alumina-silica) with the silica/alumina catalyst improves selectivity towards aromatics. These catalysts have both Fewis and Bronsted acid sites that promote carbonium ion formation. An important structural feature of zeolites is the presence of holes in the crystal lattice, which are formed by the silica-alumina tetrahedra. Each tetrahedron is made of four oxygen anions with either an aluminum or a silicon cation in the center. Each oxygen anion with a -2 oxidation state is shared between either two silicon, two aluminum, or an aluminum and a silicon cation. 

E. C. (1988b). Incorporation of the major outer membrane protein of Neisseria gonorrhoeae in saponin-Upid complexes (Iscoms) Chemical analysis, some structural features, and comparison of their immunogenicity with three other antigen delivery systems, Inf. Immun., 56, 432-438. 

Incorporation into a Polymer Layer In recent years a new electrode type is investigated which represents a layer of conducting polymer (such as polyaniline) into which a metal catalyst is incorporated by chemical or electrochemical deposition. In some cases the specific catalytic activity of the platinum crystallites incorporated into the polymer layer was found to be higher than that of ordinary dispersed platinum, probably because of special structural features of the platinum crystallites produced within the polymer matrix. A variant of this approach is that of incorporating the disperse catalyst directly into the surface layer of a solid polymer electrolyte. 

LAJs based on liquid metal electrodes have been extensively used in different geometries and modes to incorporate and study a large number of organic compounds [76, 85, 88, 106-108, 132, 160-171]. The wide use of Hg-based electrodes relies on the properties of this metal (1) it is highly conductive, (2) it forms well-ordered SAMs in a few seconds [166], (3) its surface, as a liquid, is free of structural features that cause defects in adsorbed monolayers and (4) it can form a... 

Here the hapten (Scheme 2) is a 13-diketone, which incorporates structural features of both reactants - ketone donor and aldehyde acceptor (see below, Scheme 3) - in the aldol reaction of interest. In favorable cases the hapten reacts with the primary amino-group of a lysine residue in the complementary-determining region of an antibody to form a Schiffbase 5, which readily tautomerises to the more stable vinylogous amide 6. 

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