Polymers amino acid derivatives

A number of studies have recently been devoted to membrane applications [8, 100-102], Yoshikawa and co-workers developed an imprinting technique by casting membranes from a mixture of a Merrifield resin containing a grafted tetrapeptide and of linear co-polymers of acrylonitrile and styrene in the presence of amino acid derivatives as templates [103], The membranes were cast from a tetrahydrofuran (THF) solution and the template, usually N-protected d- or 1-tryptophan, removed by washing in more polar nonsolvents for the polymer (Fig. 6-17). Membrane applications using free amino acids revealed that only the imprinted membranes showed detectable permeation. Enantioselective electrodialysis with a maximum selectivity factor of ca. 7 could be reached, although this factor depended inversely on the flux rate [7]. Also, the transport mechanism in imprinted membranes is still poorly understood. 

Another limitation is related to the fact that synthetic poly(amino acids) have rather unfavorable material properties. For instance, most synthetic poly (amino acids) derived from a single amino acid are insoluble, high-melting materials that cannot be processed into shaped objects by conventional fabrication techniques. The often undesirable tendency to absorb a significant amount of water when exposed to an aqueous environment is another common property of many poly (amino acids) (7). Finally, high molecular weight poly-(amino acids) are best prepared via N-carboxyanhydrides which are expensive to make. Hence poly(amino acids) are comparatively costly polymers, even if they are derived from inexpensive amino acids (8). 

FIGURE 3 Schematic representation of a pseudopoly (amino acid) derived from the side chain polymerization of a dipeptide carrying protecting groups X and Y. The wavy line symbolizes a nonamide bond. In this polymer, the amino acid side chains are an integral part of the polymer backbone while the termini have become pendant chains. In the backbone, amide and nonamide bonds strictly alternate. 

The oldest method of resolving enantiomers by TLC takes advantage of the natural chiral properties of cellulose and triacetylcellulose resulting from the helical structure of the polymers (98). Amino acid derivatives have been resolved on silica gel layers impregnated with chiral acids or bases, for example. 

AMINO ACID DERIVATIVES, [NP(NHCH3)2]n MIXED SUBSTITUENT ARYLAMINO AND ALKOXY DERIVATIVES POLYMERIZATION OF ORCANO-HALO TRIMERS POLYMER-BOUND DYES... 

A Nathan, J Kohn. Amino acid derived polymers. In SW Shalaby, ed. Biomedical Polymers Designed-to-Degrade Systems. Cincinnati, OH Hanser/Gardner, 1994, pp 117-151. 

Use of Mo(CHCMe2Ph)(N-2,6-/-Pr2C6H3)(0-f-Bu)2 to Generate Amino Acid-Derived Polymers... 

Fig.10. Gibson s synthesis of amino acid-derived polymers using a defined molybdenum initiator...

A series of new amino acid derivatives having pendant nucleic acid bases was prepared by the reaction of L-lysine and L-glutamic acid with the nucleic acid bases. These amino acids were further polymerized by using the N-carboxyamino acid anhydride ( NCA ) method. Alternatively, the nucleic acid base substituted poly-L-lysines were also prepared by using polymer reactions which include the reaction of carboxyethyl derivatives of the bases onto poly-L-lysine. Physico-chemical properties of the polymers obtained were given. 

Covalent linkage of amino acid, peptide or protein moieties onto the hydrolyzed and/or oxidized polymers (Control and Oxidized starches) was examined for its ability to improve the potential for microregion lipophilicity within the carbohydrate polymer. Proteinaceous materials are often strongly surface active (39) and may, if carefully selected, contribute positively to wall material characteristics. This selection process was carried-out using maltodextrins (DE 10 and/or 25) as the carbohydrate framework and various amino acid-derived materials as the function-altering accessory, ranging from gelatin and casein proteins to simple amino acids. 

In addition to their role as the building blocks of proteins, amino acids are precursors of many specialized biomolecules, including hormones, coenzymes, nucleotides, alkaloids, cell wall polymers, porphyrins, antibiotics, pigments, and neurotransmitters. We describe here the pathways to a number of these amino acid derivatives. 

Sauvagnat, B., Kulig, K., Lamaty, E, Lazaro, R. and Martinez, J., Soluble polymer supported synthesis of a-amino acid derivatives, /. Comb. Chem., 2000, 2, 134. 

Several mechanisms for NCA polymerization have been proposed. NCAs may undergo nucleophilic attack at the amino acid carbonyl with loss of carbon dioxide to provide an amino acid derivative, which subsequently reacts with a second NCA to give dimer 1 and carbon dioxide. Dimer 1 then reacts with a third NCA and propagation continues until a high molecular weight polymer 2 is obtained.15-81 This mechanism is frequently referred to as normal NCA polymerization (Scheme 1). 

Asymmetric hydrogenation of N-acyl-x-aminocinnamic acids. Rh(I) complexes with either 1 or 2 attached to polymers with suitable swelling characteristics are very effective for asymmetric hydrogenation of dehydroamino acids. Optical yields of about 90% are possible. As expected, polymer-bound Rh(I)-l results in (R)-amino acid derivatives, whereas polymer-bound Rh(I)-2 results in (S)-amino acid derivatives. 

Synthetic protein-like polymers containing amino acids find pharmaceutical and biological applications and display self-assembly properties [174], In this aspect, both ROMP and ADMET have been used as tools for the polymerization of amino acid-based monomers. Early ROMP examples date back to 1994 with the synthesis and ROMP of amino acid-derived homochiral norbomene monomers by Coles et al [175], The molybdenum complex [Mo(=CHCMe2Ph)(=NC6H3Pr,2-2,6)(OBu )2]... 

For further elongation of the peptide chain, successive coupling reactions with other polymeric active esters may be carried out until the desired sequence is obtained. The polymeric active esters are prepared by the attachment of the N-protected amino acids or peptides to a suitable insoluble polymer. Potentially useful polymeric supports in this case should carry a free hydroxyl function to which the carboxyl group of the amino acid derivatives may be coupled. Crosslinked poly(4-hydroxy-3-... 

The success of both the stepwise synthesis of peptides on a cross-linked polystyrene support (which involves the reaction of a low molecular amino acid derivative to a polymer-bound amino group) and the polymer reagent technique (where the growing... 

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