Lipases polyamide synthesis

Despite the feasibility of making and breaking amide bonds using lipases in small molecules, the use of lipases in polyamide synthesis is still very limited. The prime... 

In this work we have shown that it is possible to use an ezyme to catalyze the polycondensatioh reaction to form polyamides. The large number of polyamides that have been made indicate diat lipases from Candida antarctica and Mucor miehei are rather nonspecific and can be used generally for polyamide synthesis. In a particular example, a water-soluble polyamide has been produced from dimethyl adipate and ethylene triamine via this enzyme-catalyzed reaction at 50-110°C. The enzymatic polymerization is easy to do and... 

Poojari, Y Clarson, S. J., Lipase-Catalyzed Synthesis and Properties of Silicone Aromatic Polyesters and Silicone Aromatic Polyamides. Macromolecules 2010,43, 4616-4622. 

Hydrolysis of Copolyamide-esters (CPAEs) by Lipase (jj,). CPAEs were synthesized by the amide-ester interchange reaction between polyamide and polyester. The length of the polyamide blocks was measured after hydrolysis of ester bonds in CPAE by alkali at 30 C. The infrared spectra after hydrolyzing ester bonds on CPAEs showed that the ester bonds were almost completely removed. The molecular weight distribution of polyamide blocks was examined by GPC (Table II). The following samples were used CPAE-1 (reaction time for synthesis, 1 hr) and CPAE-2 (reaction time, U hr) composed of nylon 6 and PCL at a 50/50 molar ratio, CPAE-3 (reaction time, 1 hr) and CPAE-U (reaction time,... 

Three general approaches involving isolated enzymes have been used for polyamide or polypeptide synthesis. The first approach uses protease and other proteolytic enzymes. The second approach uses lipases and esterases. These two approaches account for most of the papers in the literature. The proteases and the lipases used tend to have relatively broad substrate specificity and can be applied to the synthesis of different types of polyamides and polypeptides. The third approach includes enzymes other than proteases and lipases. For example, in protein synthesis there has been much research into the use of cell-free extracts to produce proteins in vivo. In a few cases, the enzyme(s) responsible for the synthesis have been isolated and used to produce the same or similar proteins in vitro. Selected publications have been included in this review. 

In contrast, lipases have been used for the synthesis of both oligoamides and polyamides. Under suitable reaction conditions, lipases appear to be good catalysts for higher-molecular-weight polymers for both condensation and ringopening polymerizations. Optimization is still needed, and further developments will hopefully extend the scope of the reaction. 

As for enzymes other than proteases and lipases, only a few examples of enzyme-catalyzed synthesis of polyamides can be gleaned from the literature. 

In contrast to polyesters, very few publications deal with enzymatic synthesis of polyamides. Gu et al 24) discovered a process of using lipase at high temperatures in a single-step reaction to produce high molecular weight polyamides. A large number of polyamides were made enzymatically, including a few that could not be synthesized via chemical means. 

Frampton, MB Zelisko, PM. Synthesis of lipase-catalysed silicone-polyesters and silicone-polyamides at elevated temperatures. Chemical Communications, 2013, v. 49,9269-9271. 

Enzymatic polymerization has emerged in the last few decades as a field of considerable interest and commercial promises. It proceeds with high regio-, enantio-, and chemos-electivity under relatively mild conditions. So far, enzymes have been used to synthesize polyesters, polysaccharides, polycarbonates, polyphenols, polyanilines, vinyl polymers, and poly(amino acid)s. Namely, the lipase B of Candida antarctica (Cal-B, a serine hydrolase) immobilized on polyacrylic resin (Novozyme 435) has proven to be a very versatile catalyst in terms of reaction conditions and acceptance of various substrates. For example, this enzyme has been successfully used to synthesize polyesters. ° However, little has been reported so far on the synthesis of polyamides catalyzed by enzymes. " ... 

Scheme 2.5 Lipase (Novozym-435)-catalyzed synthesis of silicone aromatic polyamide (SAPA) by polyamidation of a,W-(diaminopropyl)-terminated poly(dimethylsiloxane) with dimethyl terephthalate in toluene at 80°C imder reduced pressure [27]. Reproduced with permission...

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