Synthetic polypeptides structure

Salcalonin, a synthetic polypeptide structurally similar to natural salmon calcitonin, is sold under the trademarks Catsynar, Miacalcic and Tonocalcin. See also Elcatonin. 

The first elastomeric protein is elastin, this structural protein is one of the main components of the extracellular matrix, which provides stmctural integrity to the tissues and organs of the body. This highly crosslinked and therefore insoluble protein is the essential element of elastic fibers, which induce elasticity to tissue of lung, skin, and arteries. In these fibers, elastin forms the internal core, which is interspersed with microfibrils [1,2]. Not only this biopolymer but also its precursor material, tropoelastin, have inspired materials scientists for many years. The most interesting characteristic of the precursor is its ability to self-assemble under physiological conditions, thereby demonstrating a lower critical solution temperature (LCST) behavior. This specific property has led to the development of a new class of synthetic polypeptides that mimic elastin in its composition and are therefore also known as elastin-like polypeptides (ELPs). 

Recent progress in novel micellar structures, including micelles containing exotic blocks such as natural or synthetic polypeptides and metal-containing segments, micelles from ABC triblock copolymers, Janus micelles and other noncentrosymmetric micelles, micelles based on interpolyelectrolyte or other noncovalent complexes, and metallosupramolecular micelles, will be discussed in Sect. 7. 

The Nishino studies represented the first attempt to incorporate flavin functionality into a synthetic and structured polypeptide motif. As with the Kaiser systems, it is possible that the observed rate enhancements are a result of the association of the hydrophobic substrates with the hydrophobic core of the bundles. The use of SDS to increase accessibility to the flavin would seem to support this. However, it is also possible that the placement of the flavin into the hydrophobic core has decreased its reduction potential and that the SDS interacts with the bundle to create a slightly more hydrophilic environment for the flavin while preserving some of the hydrophobicity for substrate binding. 

The inherent drawbacks of the oxidative refolding approach for synthetic polypeptides containing multiple cysteine residues is the individual behavior of each peptide that derives from the encoded sequence, more or less pronounced structural information which prevents general procedures to be elaborated and proposed. Nevertheless, this synthetic approach remains attractive because of its simplicity compared to the synthetic strategies for re-gioselective disulfide bond formation (Section 6.1.1-6.1.4), and it is certainly indispensable if the number of cysteine residues exceeds the presently available chemistry for site-directed cysteine pairings. 

Quantification of ORD and CD Data. In principle ORD and CD can be used to calculate the amounts of a, / , and random conformations in protein, but in practice such estimates are subject to large errors. The Moffitt-Yang plot is probably the best estimate of percentage of a-helicity, but it is unable to distinguish between the ft and random structures. A detailed analysis of CD bands and their resultant Cotton effects, combined with infrared data, is the most promising approach even here the limits of error are large (82). Traditional estimates have been based on combinations of a-helix and random coil, and attention has been centered upon estimation of helical content. Consideration of j3 structure has been introduced more recently. The technique must be calibrated empirically with synthetic polypeptides of known conformation, and the proper choice of reference is not obvious. The /3 structure seems to be particularly variable in its rotational properties (27, 82). 

Studies of synthetic polypeptides as well as examination of known protein structures reveal that some amino acids, e.g., Glu, Ala, Leu, tend to promote a helix formation. Others, such as Tyr, Val, and lie, are more often present in (3 structure, while Gly, Pro, and Asn are likely to be found in bends 270 270a 270b The frequencies with which particular amino acids appear in helices, (3 structure, or turns were first compiled by... 

X-ray diffraction played a major role in the discovery of the structure of fibrous proteins. In most cases the fibers under study are oriented in two dimensions by stretching. In this analysis we illustrate how the technique is used to study the a form of the synthetic polypeptide poly-L-alanine. 

The synthetic polyamino acids are convenient models for chemical studies of proteins since they have the extended polypeptide structure of the proteins but are free from the complications which arise in the proteins from the large number of different side chains. The work described here has been confined to the water-soluble polyamino acids poly-D,L-alanine (PDLA), poly-a,L-glutamic acid (PGA), poly-a,D-glutamic acid, and poly-a,L-lysine, and the polyimino acid, poly-L-proline. 

Numerous studies have been undertaken to elucidate the secondary structure of soluble elastin. These studies have been performed on elastin, elastin solubilized by oxalic acid (a-elastin) or potassium hydroxide (/, -elastin). synthetic polypeptide models of elastin, and tropoelastin. Techniques used include circular dichroism, FT-Raman, and electron microscopy. No consensus has been reached on the overall structure of elastin. 

Saiki, I., Murata, J., Iida, J., et al. Antimetastatic effects of synthetic polypeptides containing repeated structures of the cell adhesive Arg-Gly-Asp (RGD) and Tyr-Ile-Gly-Ser-Arg (YIGSR) sequences. Br. J. Cancer 60 722-728, 1989. 

S. N. (1968) Studies on synthetic polypeptide antigens. XX. Genetic control of the antibody response in the rat to structurally different synthetic polypeptide antigens. J Immunol 101, 730-742. 

Copper on a synthetic polypeptide demonstrated a remarkable selectivity in alcohol dehydrogenation by virtually excluding alcohols of complex structure such as diisopropyl and diisobutyl carbinol, while admitting simple alcohols such as n-butyl, isobutyl and sec-butyl 129). 

The macromolecular chains would form random coils or would become dispersed in the form of specific conformations. It seems that the formation of liquid crystalline layers of synthetic polypeptides is one of the examples of processes where ordered structures are spontaneously formed510. Aggregates could be dissolved only in good solvents whose enthalpy of mixing is negative... 

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