Amino acid-containing polymers

Synthetic methods targeting amino acid incorporation into functional materials vary widely. Free-radical polymerization of various amino acid substituted acrylates has produced many hydrocarbon-amino acid materials [161, 162]. In separate efforts, MorceUet and Endo have synthesized and meticulously characterized a library of polymers using this chain addition chemistry [163- 166]. Grubbs has shown ROMP to be successful in this motif, polymerizing amino add substituted norbornenes [167-168]. To remain within the scope of this review, the next section wiU focus only on ADMET polymerization as a method of amino add and peptide incorporation into polyethylene-based polymers. 

Wagener and colleagues first reported the use of ADMET as a method of amino acid incorporation into polymers in 2001, and have since expanded their research to focus on the production of novel polymeric materials targeted 

ADMET polymers containing D-chiro-inositol have been prepared by polymerizing the acetonide-protected inositol diene followed by deprotection to the D-c/z/ro-inositol containing polymer [171]. Synthesis of the monomer precursor was performed using whole-cell fermentation of bromobenzene with 

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Another area of active research is the synthesis of main-chain and side-chain amino acid-containing polymers for various biological apphcations. These chiral polymers are novel structures and represent the fusion of polyolefins and peptides [55, 56[ (Scheme 6.13). 

Staubli, A., Ron, E., Langer, R., 1990. Hydrolytically degradable amino acid-containing polymers. Journal of the American Chemical Society 112,4419—4424. 

Amino acids containing nucleobases like uracil and adenine, as well as imidazole, such as / -(uraciM-yl)-a-alanine, j5-(adenin-9-yl)-a-alanine, and j8-(imidazol-l-yl)-a-alanine, can also be polycondensed by CDI in aqueous imidazole buffer solution at pH 6.8 at 0 °C. The polycondensation leads to low conversion (yields of polymer 1% after four days), but pure polypeptides resulted from the reaction. Thus, compared to other alternative procedures for polycondensation, that using CDI proved to be the most effective 503... 

Proteins are polymers of L-amino acids containing numerous chiral centres, each possessing a characteristic three-dimensional shape, or conformation. Most globular proteins such as albumins undergo extensive folding of the chains into... 

Proteins are polymers made up of amino acid units that form long chains. Amino acids are molecules that contain an amino group, NH, and a carboxyl group, COOH, which characterize carboxylic acids. All amino acids contain a simple chemical backbone consisting of a carbon atom with an amino group, a carboxyl group, and a side chain group attached to the carbon ... 

Table 1 Properties of amino acid-containing ADMET polymers I (from [169])...

Scheme 15 Amino acid-containing ADMET polymers II (from [170])...

These branched-chain aliphatic amino acids contain bulky nonpolar R-groups and participate in hydrophobic interactions. All three are essential amino acids. A defect in their catabolism leads to maple syrup urine disease (Chapter 17). Isoleucine has asymmetrical centers at both the a- and 8-carbons and four stereoisomers, only one of which occurs in protein. The bulky side chains tend to associate in the interior of water-soluble globular proteins. Thus, the hydrophobic amino acid residues stabilize the three-dimensional structure of the polymer. 

Casein is one member of the important group of natural polymers, the proteins. These materials bear a formal resemblance to the polyamides in that they contain representing -CONH groups and could be formally cmisidered as polymers of amino acids. Unlike polymers such as nylon 6 and nylmi 11a number of different a-amino acids are found in each molecule whereas the nylons 6 and 11 have only one m amino acid molecule (Fig. 5). 

Proteins are polymers of amino acids. These polymers are chains, each containing him-dreds or thousands of amino acids, that fold up into a three-dimensional structure. 

The direct asymmetric aldol reaction has been studied with different di- and tri-peptides sequences supported in PEG-polystyrene resins by two different groups. In both cases the peptides contained proline at the N-terminus. In one case the other components of the sequence were aromatic amino acids. Thus, polymer 146 (20mol.%) displaying the sequence H-D-Pro-Tyr-Phe-PS produced the aldol product in 90% yield and 33% ee. The enantioselectivity was improved to 73% ee with the addition of 20 mol.% ZnCl2, but required longer reaction times. In the second case, a higher variation of amino acids was considered. Resin 147... 

Proteins are naturally occurring polymers of a-amino acids (Chapter 23). Three of the 20 most common naturally occurring amino acids contain heterocyclic rings Proline contains a pyrrolidine ring, tryptophan contains an indole ring, and histidine contains an imidazole ring. 

Proteins are polymers of amino acids that are linked by peptide bonds. All amino acids contain an amino group (-NHj) and a carboxyl group (-COOH). Dipeptides are formed when two amino acids are joined together by peptide bonds. Several covalently linked amino acids are referred to as polypeptides. Proteins can have one or more polypeptides. 

Thiolated polymers, also termed thiomers, are conventional mucoadhesive polymers chemically modified to contain a cysteine residue in the polymer chain and thus establish covalent disulfide bonds with mucin." They can be manufactured to be either cationic (mostly thiolated chitosans) or anionic (carboxylic acid-containing polymers) however, their mucoadhesive extent will mostly be determined by their capacity to covalently bind to mucin. The polypeptide backbone of mucin can be divided into three major subunits tandem repeat array, carboxyl-, and amino-terminal domains. While the amino-terminal domain contains some of the cysteine residues, the carboxyl-terminal domain contains more than 10% of the cysteine residues. These cysteine-rich regions are responsible for forming the large mucin oligomers and ultimately, the groups that allow for the covalent mucoadhesive bond formation with oral mucosal systems." ... 

The two main commercial polyamides are nylon 6,6, produced by condensation polymerization of HMD and adipic acid (see Table 7.1), and nylon 6, an AB-type polymer, which is produced from caprolactam. Other commercial polyamides include nylons 4,6, nylon 6,12 (which are AA- and BB-type polymers) and nylon 11 and nylon 12 (which are AB polymers made from linear aliphatic amino acids containing 11 and 12 carbons, respectively) [1]. Polyamides are also produced using monomers with aromatic, rather than aliphatic segments. Polyamides that contain 85% or more of the amide bonds attached to aromatic rings are called aramids. Commercial examples include poly(p-phenyleneterephthalamide) or Kevlar and poly(m-phenyleneisoterephthalamide) or Nomex [23]. 

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