Polyesters enzymes

Mueller RJ (2006) Biological degradation of synthetic polyesters - enzymes as potential catalysts for polyester recycling. Process Biochem 41 2124-2128... 

Sucrose polyesters, which are made by esterilying sucrose with long-chain fatty acids, have the physical properties of fat, but are resistant to digestive enzymes (40). Olestra, a sucrose polyester developed by Procter Gamble, was submitted for regulatory approval in May 1987. In order to faciUtate the approval process, Procter Gamble has since narrowed the scope of its food additive petition to include olestra s use only in savory and extmded snacks. 

Poly(ethylene carbonate). Like polyesters, polycarbonates (qv) are bioabsorbable only if the hydrolyzable linkages are accessible to enzymes and/or water molecules. Thus pellets of poly(ethylene carbonate), ( OCOOCH2CH2 )n weighing 200 mg implanted ia the peritoneal cavity of rats,... 

Fig. 6. Washing performance on different soilings of a U.S. liquid detergent (B) and a U.S. powder detergent (H in a Terg-o-tometer operating at 20°C for 10 min one enzyme dosage. EMPA 117 (nulk, blood, and ink on polyester/cotton) EMPA 116 (milk, blood, and ink on 100% cotton) grass on (100% cotton) AS 10 (milk, oil, and pigments on 100% cotton) blood soilings (on 100% cotton).

Synthetic resins Acrylic Alkyd. Chiorobenzols Chlorodiphenyls Chloro-naphthalenes Chlorophenols Cumaron Epoxies Melamine formaldehyde Phenol formaldehyde Polyesters Sulphonamide formaldehyde Urea formaldehyde Urethane Vinyl Others Enzymes derived from B. subtilis... 

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. 

Lipase is an enzyme which catalyzes the hydrolysis of fatty acid esters normally in an aqueous environment in living systems. However, hpases are sometimes stable in organic solvents and can be used as catalyst for esterifications and transesterifications. By utihzing such catalytic specificities of lipase, functional aliphatic polyesters have been synthesized by various polymerization modes. Typical reaction types of hpase-catalyzed polymerization leading to polyesters are summarized in Scheme 1. Lipase-catalyzed polymerizations also produced polycarbonates and polyphosphates. 

Lipases CA, BC, and PF catalyzed the polymerization of ethylene dode-canoate and ethylene tridecanoate to give the corresponding polyesters. The enzyme origin affected the polymerization behaviors in using lipase BC catalyst, these bislactones polymerized faster than e-CL and DDL, whereas the reactivity of these cyclic diesters was in the middle of e-CL and DDL in using lipase CA. 

Akutsu Y, T Nakajima-Kambe, N Nomura, T Nakahara (1998) Purification and properties of a polyester poly-urethane-degrading enzyme from Comamonas acidovorans TB-35. Appl Environ Microbiol 64 62-67. 

Chlorophenols Cumaron Epoxies Melamine formaldehyde Phenol formaldehyde Polyesters Others Enzymes derived from B. subtilis... 

When polyester-hydrolyzing activity was isolated using synthetic polyesters such as polycaprolactone, and the enzyme was examined in detail, it was found that it was a cutinase that was responsible for the hydrolysis [113]. Similarly, the polyester domains of suberin were found to be degraded by cutinase. Cutinase is a polyesterase, and similar enzymes may be widely distributed and can degrade a variety of natural and synthetic polyesters. Microbial polyhydroxy-alkanoic acids that are attracting increasing attention as biodegradable polyesters can be hydrolyzed by bacterial polyesterases that share some common features with cutinases [114] and this area is covered in another chapter [115]. 

From this perspective it would be interesting to discover if there is a relationship between the substrate used and the concentration of free CoA under conditions of unlimited growth. If there is, depending on the source of carbon and energy used and the K value of the 3-ketothiolase for CoASH, cell multiplication and poly(3HB) accumulation can occur simultaneously [60,61]. If this enzyme is not involved, poly(3HB) [29] and other polyesters [28,29] can also be synthesized during growth. 

In vitro synthesis of polyesters using isolated enzymes as catalyst via non-biosynthetic pathways is reviewed. In most cases, lipase was used as catalyst and various monomer combinations, typically oxyacids or their esters, dicarboxylic acids or their derivatives/glycols, and lactones, afforded the polyesters. The enzymatic polymerization often proceeded under mild reaction conditions in comparison with chemical processes. By utilizing characteristic properties of lipases, regio- and enantioselective polymerizations proceeded to give functional polymers, most of which are difficult to synthesize by conventional methodologies. 

Fig. 1. Typical routes of polyester production using an isolated enzyme as catalyst...

Syntheses of aliphatic polyesters by fermentation and chemical processes have been extensively studied from the viewpoint of biodegradable materials science. Recently, another approach to their production has been made by using an isolated lipase or esterase as catalyst via non-biosynthetic pathways under mild reaction conditions. Lipase and esterase are enzymes which catalyze hydrolysis of esters in an aqueous environment in living systems. Some of them can act as catalyst for the reverse reactions, esterifications and transesterifications, in organic media [1-5]. These catalytic actions have been expanded to... 

The copolymerization of lactones took place through enzyme catalysis [92]. The copolymerization of e-CL with d-VL catalyzed by lipase PF affords the corresponding copolymer having a molecular weight of several thousand. From 13C NMR analysis, the copolymer was found to be of random structure having both units, suggesting the frequent occurrence of transesterifications between the polyesters. In the copolymerization of 8-OL with e-CL or DDL, random copolyesters were also formed [84], whereas the copolymer from e-CL and PDL was not statistically random [88]. 

In vitro polyester syntheses using an isolated enzyme as catalyst via non-bio-synthetic pathways is reviewed. These enzymatic routes for production of biodegradable polyesters possess several advances in comparison with fermentation and chemical processes ... 

Polyesters, such as microbially produced poly[(P)-3-hydroxybutyric acid] [poly(3HB)], other poly[(P)-hydroxyalkanoic acids] [poly(HA)] and related biosynthetic or chemosynthetic polyesters are a class of polymers that have potential applications as thermoplastic elastomers. In contrast to poly(ethylene) and similar polymers with saturated, non-functionalized carbon backbones, poly(HA) can be biodegraded to water, methane, and/or carbon dioxide. This review provides an overview of the microbiology, biochemistry and molecular biology of poly(HA) biodegradation. In particular, the properties of extracellular and intracellular poly(HA) hydrolyzing enzymes [poly(HA) depolymerases] are described. 

Although there is evidence that all poly(HA) depolymerases cleave the polyesters by the same mechanism (catalytic triad), the poly(3HO) depolymerase differs considerably from poly(HASCL) depolymerases in terms of primary sequence and polymer-binding. This might be due to different approaches of these enzymes to get access to the polymers reflecting the distinctive physicochemical properties of poly(HASCL) and poly(HMCLA) rather than coevolution. 

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