Poly peptid composition

There remains to be considered the relation of the poly-peptides to the proteins and the probable constitution of the proteins. The study of proteins on which the above classification is based has been almost wholly that of their composition and physical properties. 

In Section 7.7.3.3, methods for quantitating a-helix and other secondary structural types in peptides were described. These are generally applicable to a series of peptides in which a regular conformation [a-helix, (3-sheet, poly(Pro)II] is in equilibrium with an ensemble of unordered conformations, as evidenced by an isodichroic point observed over a range of temperature, pH, or solvent composition. 

A host of bioadhesive controlled release systems have been proposed in recent years. Among the most commonly studied applications of bioadhesive materials is the area of buccal controlled delivery [408], The buccal delivery of small peptides from bioadhesive polymers was studied by Bodde and coworkers [409], and a wide range of compositions based on poly(butyl acrylate) and/or poly(acrylic acid) gave satisfactory performance. Bioadhesive poly(acrylic add)-based formulations have also been used for oral applications [402,410] for the sustained delivery of chlorothiazide [410] and for a thin bioadhesive patch for treatment of gingivitis and periodontal disease [411]. Other bioadhesive applications of polyelectrolytes include materials for ophthalmic vehicles [412,413], and systems for oral [410,414,415-419], rectal [420,421] vaginal [422] and nasal [423] drug delivery. 

There are no accurate determinations of the overall contributions of peptide components to the compositions of HS and of SOM. The difficulties arise from the problems of separating these from other components of the SOM mixtures. Use of DMSO + 1% 12M HC1 and XAD-8 resin [(poly)methylmethacrylate] technology enabled Appelqvist et al. (1996) to decrease the amino acid content of a HA by 23%, and the decrease was uniform for the different amino acid groupings. This still left considerable amounts of peptide material in association with the HAs. Some may well have been in association with the humic matrix, and some may have been covalently linked to the humic core through, for example, the formation of Schiff... 

Shamby et al. described a surface finish that consists of a water-insoluble composite of silver bromide nanoparticles and poly(4-vinylpyridinium) salts. Again, silver is released and the quarternary ammonium groups kill on contact [139], Gyomard et al. incorporated the natural antimicrobial peptide gramicidin A into a LbL matrix and were able to show, that the peptide kills Enterococcus faecalis in the surroundings when released and on the surface in immobilized form [140], It is also possible that the antimicrobial a-poly-L-lysine in the LbL layer helped a little. 

There are a couple of polyethylene-based composites that have shown some success in solid-phase organic synthesis. Merrifield and co-workers [32] introduced a polystyrene-polyethylene composite support in the form of a sheet for solid-phase peptide synthesis, which exhibited an amine loading level of 1.0 mmol amine/g. This material has since been molded into various shapes, including tubing for a continuous-flow peptide synthesizer (reported loading=0.21 mmol amine/m tube or 0.67 mmol amine/g) [33], Geysen and coworkers [34,35] synthesized a poly ethylene-polymethaciy late copolymer which was molded... 

New photoresponsive polymers and peptides have been developed by incorporation of an azobenzene chromophore. The photochemistry of azobenzene-containing polymers has been reviewed,and the ion-conducting polymer composite film of poly(vinyl chloride)/the azobenzene liquid crystal (4)/lithium perchlorate is a promising material for use in photoinduced image storage.Photoisomerization has also been demonstrated... 

Hanlon (1966) has presented spectra for poly-y-benzyl-L-glutamate in systems of varying solvent composition of dichloroacetic acid and ethylene dichloride. The 1.51 /i band indicates protonation of the peptide residues. Poly-y-benzyl-L-glutamate exhibits a unique protonation pattern characterized by two transition regions one at low concentrations of acid, and the other between concentrations of 75 % and 80% acid only the latter transition can be reversed by an increase in temperature within the range 11 to 55 C. This unique protonation pattern parallels that found with measurements of other physical properties of poly-y-benzyl-L-glutamate in this solvent system. 

Hanlon and Klotz (1968) have discussed the use of near-infrared spectroscopy for studying structural problems of biochemistry. In particular, they have considered the equilibrium state of the peptide unit in a number of synthetic polyamino acids (poly-L-alanine, poly-L-leucine, poly-L-methionine, and poly-y-benzyl-L-glutamate) as a function of solvent composition under conditions where the transitions in other physical properties of these polymers have been interpreted as simple peptide, hydrogen-bonded, helix-to-coil transitions. Their spectral data demonstrate that these conversions involve protonated peptide species and are far more complicated than investigators of these processes had assumed. 

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