Enzymatic synthesis poly

In the beginning of the investigation it was believed that enzymatic synthesis of j8-poly(L-malate) follows a route, which is similar to the synthesis of poly(j8-hydrox-ybutyrate) (for a review see [15]). However, enzymati-... 

C. Oligo- and Poly-nucleotides.—The stepwise enzymatic synthesis of internucleotide bonds has been reviewed. A number of polynucleotides containing modified bases have been synthesised " in the past year from nucleoside triphosphates with the aid of a polymerase enzyme, and the enzymatic synthesis of oligodeoxyribonucleotides using terminal deoxynucleotidyl transferase has been studied. Primer-independent polynucleotide phosphorylase from Micrococcus luteus has been attached to cellulose after the latter has been activated with cyanogen bromide. The preparation of insolubilized enzyme has enabled large quantities of synthetic polynucleotides to be made. The soluble enzyme has been used to prepare various modified polycytidylic acids. ... 

Enzymes are generally classified into six groups. Table 1 shows typical polymers produced with catalysis by respective enzymes. The target macromolecules for the enzymatic polymerization have been polysaccharides, poly(amino acid)s, polyesters, polycarbonates, phenolic polymers, poly(aniline)s, vinyl polymers, etc. In the standpoint of potential industrial applications, this chapter deals with recent topics on enzymatic synthesis of polyesters and phenolic polymers by using enzymes as catalyst. 

Enzymatic synthesis of aliphatic polyesters was also achieved by the ringopening polymerization of cyclic diesters. Lactide was not enzymatically polymerized under mild reaction conditions however, poly(lacfic acid) with the molecular weight higher than 1 x 10" was formed using lipase BC as catalyst at higher temperatures (80-130°C). Protease (proteinase K) also induced the polymerization however, the catalytic activity was relatively low. 

The enzymatic polymerization of lactones could be initiated at the hydroxy group of the polymer, which expanded to enzymatic synthesis of graft copolymers. The polymerization of c-CL using thermophilic lipase as catalyst in the presence of hydroxyethyl cellulose (HEC) film produced HEC-gra/f-poly( -CL) with degree of substitution from 0.10 to 0.32 [102]. 

Fig. 11. Enzymatic synthesis of poly( -CL) monosubstituted first generation dendrimer...

First, the short chain length PHAs, poly(HASCL), are composed of monomeric units containing up to 5 carbon atoms. The most well-known representatives are poly(3-hydroxybutyrate) (PHB), and its copolymers with hydroxyvalerate. Of all the PHAs, PHB is by far the most commonly encountered in nature [18]. It is the simplest PHA with respect to chemical structure, having a methylene (-CH3) group as the pendent R-unit in Fig. 1. Owing to its enzymatic synthesis, PHB has an exceptional stereochemical regularity. The chains are linear and the chiral centers all are in the R-stereochemical conformation, which implies that this polymer is completely isotactic. 

Alva KS, Kumar J, Marx KA, Tripathy SK (1997) Enzymatic synthesis and characterization of a novel water-soluble polyanihne poly(2,5-diaminobenzenesulfonate). Macromolecules 30(14) 4024 029... 

Rumbau V, Pomposo JA, Eleta A, Rodriguez J, Grande H, Mecerreyes D, Ochoteco E (2007) Eirst enzymatic synthesis of water-soluble conducting poly(3,4-ethylenedioxythiophene). Biomacromolecules 8(2) 315-317... 

Figure 10.3 Enzymatic synthesis of poly(adenylic acid) in self-reproducing oleate liposomes (redrawn from Walde et al., 1994a). (a) The ADP penetrates (sluggishly) the liposome bilayer, (b) in the presence of polynucleotide phosphorylase, ADP is converted in poly(A), which remains entrapped in the liposome, (c) Polycondensation of ADP goes on simultaneously with the self-reproduction of liposomes (A is the membrane precursor, oleic anhydride, which, once added, induces the self-reproduction of liposomes S, surfactant, in this case oleate, which is the hydrolysis product of A on the bilayer E is polynucleotide phosphorylase).

A different example of enzymatic synthesis in vesicles was also mentioned in the previous chapter the polycondensation of adenonine diphosphate (ADP) into poly(A) by encapsulated enzymes (Chakrabarti et al, 1994 Walde et al, 1994a). In the case of Walde et al. (1994a) there was a core-and-shell reproduction, as the synthesis of poly(A) - a prototype of RNA - was occurring simultaneously with the self-reproduction of the vesicle shells (see Figure 10.3). 

Walde, R, Goto, A., Monnard, P.-A., Wessicken, M., and Luisi, P. L. (1994a). Oparin s reactions revisited enzymatic synthesis of poly(adenylic acid) in micelles and self-reproducing vesicles. J. Am. Chem. Soc., 116, 7541-7. 

Figure 2.14. Possible reaction sequence of polymer formation from catechol by peroxidase. Reprinted from Dubey, S., Singh, D., and Misra, R. A. (1998). Enzymatic synthesis and various properties of poly(catechol). Enzyme Microb. Technol. 23, 432-437, with permission from Elsevier.

Nabid MR, Entezami AA (2003) Enzymatic synthesis and characterization of a water-soluble, conducting poly(o-toluidine). Eur Polym J 39 1169-1175... 

Murata T, Honda H, Hattori T, Usui T. Enzymatic synthesis of poly-A -acetyllactosamines as potential substrates for 23. 

Gorke JT, Okrasa K, Louwagie A, Kazlauskas RJ, Srienc F (2007) Enzymatic synthesis of poly(hydroxyalkanoates) in ionic liquids. J Biotechnol 132 306-313... 

Scheme 4.14 Enzymatic synthesis of end-functionalized poly(caprolactone) monomers using carboxylic acid as chain-terminating group.

Particles of the enzymatically synthesized phenolic polymers were also formed by reverse micellar polymerization. A thiol-containing polymer was synthesized by peroxidase-catalyzed copolymerization of p-hydroxythiophenol and p-ethylphenol in reverse micelles [70], CdS nanoparticles were attached to the copolymer to give polymer-CdS nanocomposites. The reverse micellar system was also effective for the enzymatic synthesis of poly(2-naphthol) consisting of qui-nonoid structure [71], which showed a fluorescence characteristic of the naphthol chromophore. Amphiphilic higher alkyl ester derivatives were enzymatically polymerized in a micellar solution to give surface-active polymers at the air-water interface [72, 73]. 

In the polymerization of catechin by using laccase (ML) as catalyst, the reaction conditions were examined in detail [112], A mixture of acetone and acetate buffer (pH 5) was suitable for the efficient synthesis of soluble poly(catechin) with high molecular weight. The mixed ratio of acetone greatly affected the yield, molecular weight, and solubility of the polymer. The polymer synthesized in 20% acetone showed low solubility toward DMF, whereas the polymer obtained in the acetone content less than 5% was completely soluble in DMF. In the UV-Vis spectrum of poly(catechin) in methanol, a broad peak centered at 370 nm was observed. In alkaline solution, this peak was red-shifted and the peak intensity became larger than that in methanol. In the ESR spectrum of the enzymatically synthesized poly (catechin), a singlet peak at g= 1.982 was detected, whereas the catechin monomer possessed no ESR peak. 

Li, S. and Liu, X., 2008. Synthesis, characterization, and evaluation of enzymatically degradable poly(N-isopropylacrylamide-co-acrylic acid) hydrogels for colon-specific drug delivery. Polymers for Advanced Technologies, 19, 1536-1542. 

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