Synthetic polyamino acids

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. 

Polyelectrolyte complexes of retinoic acid have been well investigated, they are pharmaceutically active surfactants. In the following, we will therefore discuss the physicochemical properties of drug carriers formed by synthetic polyamino acids, polyethyleneimine, double hydrophilic block copolymers and retinoic acid. 

The six number for a peptide bond formed by residues A and B, is obtained by adding the number of atoms in A and B. Thus, in alanylglycine, the six number is zero since the atoms in the side chains of alanine and glycine do not occupy position 6, whereas the six number for valylglycine is 6 since atoms in the side chain of valine occupy position 6 of the dipeptide. Peptides with a six number of 6, such as valylglycine or leucylleucine, are hydrolyzed slowly, whereas those with numbers of 3 are hydrolyzed at intermediate rates and those with numbers of zero, are hydrolyzed most rapidly. The six numbers of the dipeptides examined by Synge (1945) as well as those for some synthetic polyamino acids (Heyns et al., 1958) correlate fairly well with the experimentally determined relative... 

A. Complexes of Synthetic Polyamino Acids with Various Molecules 82... 

The parameters given may differ to some extent for various systems, since these values were obtained for synthetic polyamino acids and may not be applicable to many protein systems [e.g., (63, 59, 64, 60, 65—68)]. 

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. 

Most P. also contain a large number of amino acid residues which cannot be assigned to any regular structure. Only certain peptide conformations are possible others would bring neighboring unbonded atoms too close together (see Ramachandran plot). The fully denatured state of a polypeptide is referred to as a random coil this completely disordered structure is also found in helix-coil transitions and in synthetic polyamino acids... 

One of the early examples for organocatalysis is the asymmetric Weitz-Scheffer epoxidation of electron-deficient olefins, which can be effected either by organic chiral phase transfer catalysts (PTC) under biphasic conditions or by polyamino acids. This reaction has gained considerable attention and is of great synthetic use. 

Julia, S., Guixer, J., Masana, J., Rocas, J., Colonna, S., Annuziata, R. and Molinari, H. Synthetic enzymes. 2. Catalytic asymmetric epoxidation by means of polyamino-acids in a triphase system, J. Chem. Soc., Perkin Trans. 1, 1982, 1317-1324. 

The specificities of antibodies to proteins and polysaccharides, proteins, and polyamino acids, and nucleic acid and synthetic polymers are discussed in detail. 

The third principal type of fibrous materials comprises the synthetic polymers. Unlike natural fibers, which apparently are always H bonded, some synthetic fibers are not H bonded. The polyamides form the best example of man-made H bonded polymers. These include nylons or polyamides, polyamino acids, polythioamides, polyurethanes, and some less well known polymers of substituted urea, hydrazide, aminotriazole, sulfonamide, or others. Specialized reference books are available (954). 

Polymers are ubiquitous. Natural polymers such as proteins (polyamino acids), DNA (polynucleotides), and cellulose (polyglucose) are the basic building blocks of plant and animal life. Synthetic organic polymers, or plastics, are now among our most common structural materials. In the United States we make and use more synthetic polymers than we do steel, aluminum, and copper combined—in 1984, 46 billion pounds, worth 18 billion dollars. 

Synthetic polymers Polyamide Polyamino acids, Polypeptides... 

Since 1954, a newer type of synthetic approach has been used for preparing poly-a-amino acids. This method, as detailed by Fox and Harada (6), employs the simplest of reaction conditions, requiring only initially dry amino acids and temperatures above the boiling point of water. A wide variety of polyamino acids has been prepared by this method, including many that contain some proportion of each of the 18 common proteinogenous amino acids, as reviewed by Fox (7). 

The thermal polymers are incapable of mimicing a peptide or protein to the exact extent that the product of a stepwise synthesis does. An exact duplication of a functional protein, however, does little to elucidate the reason for its activity modification and study of the effect on activity are necessary. Systematic synthetic modification of polymeric models is easily achieved in the case of thermal polyamino acids. They are prepared with much ease and in large numbers, and their quantitative compositions can be regulated and controlled simply. Examples are already at hand to illustrate the use of the thermal method to evaluate qualitatively the kinds of amino acid residue that are necessary for, contributory to, or detrimental to, activity. Such studies augment information from enzymes and from nonthermal models. 

Sequence polymers synthetic amino acid polymers, consisting of multiple repeats of one short sequence. In contrast to Polyamino acids (see), Sp. contain more than one type of amino acid residue. They are prepared by the self condensation of activated peptides (di to hepta). p-Nitrophenyl esters (see Peptid ) and other activated esters can be u ring closure is avoided by using high concentrations of reactants in polar solvents in the presence of organic bases. The average of the resulting S.p. are considerably lower than those of the synthetic poly-... 

Condensation polymers are formed by the reaction of bifunctional or poly functional molecules, with the elimination of some small molecule (such as water, ammonia, or hydrogen chloride) as a by-product. Familiar examples of synthetic condensation polymers include polyesters (Dacron, Mylar), polyamides (nylon), polyurethanes, and epoxy resin. Natural condensation polymers include polyamino acids (protein), cellulose, and starch. The process can be represented as follows ... 

Synthetic polymers. Polylactic acid (PLA), polyglycolic acid (PGA), polycaprolactone (PCA), polyamino acids, polyethylene (PE) and high molecular weight derivatives, polysulfone, polyhydroxybutyrate. 

As a synthetic application of the polyamino-acid-catalyzed epoxidation, scientists at SmithKline Beecham Pharmaceuticals (London, U.K.) developed a highly... 

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