Poly-L-amino acids

When a poly-(L)-amino acid is used in the epoxidation of chalcone, the predominant optical isomer is laevorotatory [10]. The laevorotatory enantiomer of epoxychalcone has been shown [7] to have absolute configuration 2R, 3S). As anticipated, the use of a poly-(D)-amino acid as the epoxidation catalyst gives rise to the dextrorotatory enantiomer [10]. 

Given that all of the optically active epoxides in Tables 1 and 2 synthesised using poly-(l)-amino acids are laevorotatory, their absolute stereochemistry has... 

Polymeric micelles formed by Pluronics, PEG phospholipid conjugates, PEG-b-polyesters, or PEG-b-poly-L-amino acids were proposed for drug delivery of poorly water-soluble compounds, such as amphotericin B, propofol, paclitaxel, and photosensitizers [77,86,87]. It was also emphasized that using polymeric micelles can significantly increase the drug transport into the brain. 

Lavasanifar, A., J. Samuel, and G.S. Kwon. 2002. Polyethylene oxide)-block-poly(L-amino acid) micelles for drug delivery. Adv Drug Deliv Rev 54 169. 

In addition to this we have several examples of which the polymer conformation of the polymeric complex leads the asymmetrical selectivity Hydrogenation reactions of 1-methylcinnamic acid and 1-acetamidocinnamic acid by several poly(L-amino acid)-Pd complexes are observed (142-144). Poly(L-valine) (/3-form) and poly(/3-benzyl-L-aspartate) (a-helix, sinistral) give dextrorotative products, and poly(L-leucine) and poly( 3-benzyl-L-aspartate) (a-helix, dextral) do levo-rotatory products. Also, optical active poly-/3-hydroxyl esters-Raney Ni catalyst (145) and Ion-exchange resin modified by optical active amino acid-metal complex (146,147) are observed in asymmetrically selective hydrogenations. 

Another method is to use poly-L-amino acids as catalysts in alkaline media (Julia-Colanna epoxidation) for the asymmetric epoxidation of chalcones and other electron-poor olefins with H202 [287]. SmithKline Beecham workers used this method (see Fig. 4.105) as a key step in the synthesis of a leukotriene antagonist, although it required 20 equivalents of H202 and 12 equivalents of NaOH, based on substrate [288]. The mechanism probably involves the asym-... 

Hayase, F., Kato, H., and Fujimaki, M. (1975). Racemization of amino acid residues in proteins and poly(L-amino acids) during roasting. J. Agric. Food Chem. 23, 491-494. 

Adams, M.L. Andes, D.R. Kwon, G.S. Amphotericin b encapsulated in micelles based on poly(ethylene oxide)-block-poly(l-amino acid) derivatives exerts reduced in vitro hemolysis but maintains potent in vivo antifungal activity. Biomacromolecules 2003, 4, 750-757. 

Zunino F, Savi G, Giuliani F, et al. Comparison of antitumor effects of daunorabicin covalently linked to poly-L-amino acid carriers. Eur J Cancer Clin Oncol 1984 20 421-425. 

Jarerat, A., Tokiwa, Y. and Tanaka, H. (2004) Microbial poly(L-lactide)-degrading enzyme induced by amino acids, peptides and poly(L-amino acids). Journal cf Polymers and the Environment, 12, 139-146. 

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)... 

Our research group has reported in a series of papers that production of enzymes from PLLA degrading microorganisms was induced when some proteins such as silk fibroin, elastin, gelatin, peptides, and some amino acids were present in the cultivation medium [27, 44—46, 48]. For instance, a significant increase in the enzyme activity of Amycolatopsis strain HT-41 was detected when silk fibroin was added into the culture medium [44]. Moreover, various amino acids, peptides, and poly(L-amino acids) were used as enzyme inducers for the production of enzymes from T. albtm, L. waywandensis, and A. orientalis. Silk fibroin was found to be the best inducer for A. orientalis. On the other hand, the enzyme activities of L. waywandensis and T. album were stimulated by elastin but not by silk fibroin. Soluble culture substrates such as peptides and amino acids had lower induction activities in comparison to protein substrates (silk fibroin, elastin, collagen, and keratin) [48]. 

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