Synthetic Poly Amino Acid s

Poly(aspartic acid) (PAA) is an ionic polymer that shows water solubility, which has been found to undergo lysosomal biodegradation. Due to the high functionality of the polymer, many block copolymers and chemically modified forms of PAA are synthesized with aspartic acid and other synthetic biodegradable polymeric moieties that form drug delivery vehicles with core-forming micellar nanostructures, and are currently xmder late stage clinical trials [39]. 

Albumin is a water-soluble protein representing 50% of total plasma mass and is the most copious protein in human blood plasma. The pre-proalbumins synthesized in the liver are further processed and released into the circulatory system. Albumin is known to degrade in all tissues in the body and shows excellent blood compatibility, making it a great choice of biodegradable polymer for medical applications [40]. Albumin can be effortlessly modified, due to the presence of functional groups and desirable solubility, into various shapes and forms such as membranes, microspheres, nanofibers and nanospheres. 

Macromolecules that are formed from number of monosaccharide units connected together by glycosidic Hnkages are polysaccharides. They own special biological 

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Synthetic poly(amino acids) possess advant s as well as disadvantages as enzyme models, when compared widi vinyl polymers. The greatest advantage is probably the structural similarity of the polymer backbone (polypeptide linkage), and conformational characteristics derived therefrom. On the odier hand, die syndietic problems are much greater than those of vinyl polymers. A review artide was recently published on tfiis subject (726). 

Enzymes may be classified generally into six groups the details of typical polymers produced via catalysis with respective enzymes are listed in Table 23.1. In the past, the target macromolecules for enzymatic polymerization have included polysaccharides, poly(amino acid)s, polyesters, polycarbonates, phenolic polymers, poly(aniline)s, and vinyl polymers. In this chapter, attention is focused on the enzymatic synthesis of phenohc polymers and polyesters, based on the increasing industrial application of these materials. Notably, most such polymers can be obtained from commercially available, inexpensive monomers by using industrially produced enzymes. Another important point is that the enzymatic process must be regarded as an environmentally benign synthetic pathway. Details of the enzymatic synthesis of other polymers are provided in recent pertinent reviews [3-10]. 

Poly(amino acid)s are synthetically derived polymers which can be obtained from a variety of animal source amino acids. The properties are largely dependent on the functionahties of their respective side chains. However, they have poor mechanical properties and are difficult to process. Modihed poly(L-lysine) and poly(L-glutamic acid) have been used to produce hybrids with bioactive molecules. ... 

Vesicles can interact with a variety of polymers, such as natural polysaccharides [42], poly(amino acid)s, or hydrophilic synthetic polymers. The... 

Polypeptides and poly(a-amino acid)s have a quite unique position amongst synthetic polymers. The reason for this is that most common synthetic polymers have very little long range order in solution and their properties are the products of statistical random coil conformations. Polypeptides, in contrast, can adopt well defined, ordered structures typical of those existing in proteins, such as a-helix and P-struc-tures. Moreover, the ordered structures can undergo conformational changes to the random coil state as cooperative transitions, analogous to the denaturation of proteins. 

Poly( a-amino acid/vis a better term for peptides formed by the self-condensation of one amino acid natural examples exist, such as poly(D-glutamic acid), the protein coat of the anthrax spore (Flanby and Rydon, 1946). In early research in the textile industry, poly(a-amino acid)s showed promise as synthetic fibres, but the synthesis methodology required for the polymerisation of amino acids was complex and uneconomic. 

T. Sedlailk, H. Studenovska, F. Rypacek, Enzymatic degradation of the hydrogels based on synthetic poly(a-amino acid)s, J. Mater. Sci. Mater. Med. 22 (2011) 781-788. 

Several synthetic polypeptides, such as the poly(L-amino acid)s, the poly(y-L-glutamate) (PBLG), poly(j8-benzyl-L-asparate) (P BA), and poly(L-glutamlc acid)... 

In one of the early experiments designed to elucidate the genetic code, Marshall Nirenberg of the U.S. National Institutes of Health (Nobel Prize in physiology or medicine, 1968) prepared a synthetic mRNA in which all the bases were uracil. He added this poly(U) to a cell-free system containing all the necessary materials for protein biosynthesis. A polymer of a single amino acid was obtained. What amino acid was polymerized ... 

Mechanistic considerations (e.g., the extensive work published on brush-type phases) or the practitioner s experience might help to select a chiral stationary phase (CSP) for initial work. Scouting for the best CSP/mobile phase combination can be automated by using automated solvent and column switching. More than 100 different CSPs have been reported in the literature to date. Stationary phases for chiral pSFC have been prepared from the chiral pool by modifying small molecules, like amino acids or alkaloids, by the deriva-tization of polymers such as carbohydrates, or by bonding of macrocycles. Also, synthetic selectors such as the brush-type ( Pirkle ) phases, helical poly(meth) acrylates, polysiloxanes and polysiloxane copolymers, and chiral selectors physically coated onto graphite surfaces have been used as stationary phases. 

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-... 

How the code has been worked out is illustrated by the following experiment. An enzyme solution obtained from bacterial cells and added to a solution of all twenty amino acids produces a polypeptide chain consisting only of residues of the amino acid phenylalanine when provided with a synthetic RNA consisting of poly-uracil (that is, U-U-U-U-. . . ). Hence UUU is the codon for phenylalanine, as shown in the table. Much of this work was done by the American scientists M. W. Nirenberg, H. G. Khorana, and R. H. Holley, and their collaborators, with use of enzymes that had been discovered by A. Kornberg and S. Ochoa. 

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