Lipase catalysis

So far, various dicarboxylic acid derivatives, dicarboxylic acids, their activated and non-activated esters, cyclic acid anhydrides, and polyanhydrides have been polymerized with glycols through lipase catalysis to give polyesters. 

Lipase-catalyzed synthesis of polyesters from cyclic anhydrides and oxi-ranes was reported. The polymerization took place by PPL catalyst and the molecular weight reached 1 x 10" under the selected reaction conditions. During the polymerizahon, the enzymatically formed acid group from the anhydride may open the oxirane ring to give a glycol, which is then reacted with the anhydride or acid by lipase catalysis, yielding the polyesters. 

Lipase catalysis is often used for enantioselective production of chiral compounds. Lipase induced the enantioselective ring-opening polymerization of racemic lactones. In the lipase-catalyzed polymerization of racemic (3-BL, the enantioselec-tivity was low an enantioselective polymerization of (3-BL occurred by using thermophilic lipase to give (/ )-enriched PHB with 20-37% enantiomeric excess (ee). ... 

Epoxide-containing polyesters were enzymatically synthesized via two routes using unsaturated fatty acids as starting substrate (Scheme 11)." Lipase catalysis was used for both polycondensation and epoxidation of unsaturated fatty acid group. One route was synthesis of aliphatic polyesters containing an... 

Reactive polyesters were enzymatically synthesized. Lipase catalysis chemoselecfively induced the ring-opening polymerization of a lactone having exo-methylene group to produce a polyester having the reactive exo-methylene group in the main chain (Scheme 16). This is in contrast to the anionic... 

Terminal-functionalized polymers such as macromonomers and telechelics are very important as prepolymer for construction of functional materials. Single-step functionalization of polymer terminal was achieved via lipase catalysis. Alcohols could initiate the ring-opening polymerizahon of lactones by lipase catalyst. The lipase CA-catalyzed polymerizahon of DDL in the presence of 2-hydroxyethyl methacrylate gave the methacryl-type polyester macromonomer, in which 2-hydroxyethyl methacrylate acted as initiator to introduce the methacryloyl group quanhtatively at the polymer terminal ( inihator method ).This methodology was expanded to the synthesis of oo-alkenyl- and alkynyl-type macromonomers by using 5-hexen-l-ol and 5-hexyn-l-ol as initiator, respechvely. 

Fig. 3. Proposed mechanism of polymerization of dicarboxylic acid divinyl ester and glycol through lipase catalysis...

Lipase catalysis induced the enantioselective polymerization, yielding optically active oligoesters and polyesters. The polymerization of racemic bis(2-chloroethyl) 2,5-dibromoadipate with excess of 1,6-hexanediol using lipase A catalyst produced optically active trimer and pentamer [46]. 

Polyester syntheses have been achieved by enzymatic ring-opening polymerization of lactide and lactones with various ring-sizes. Here, we focus not only on these cyclic esters but also other cyclic monomers for lipase-catalyzed ringopening polymerizations. Figure 8 summarizes cyclic monomers for providing polyesters via lipase catalysis. 

Several small-size (four-membered) lactones have been reported to be polymerized through lipase catalysis. The polymerization of /Tpropiolactone (/ -PL) by Pseudomonas family lipases as catalyst in bulk produced a mixture of linear... 

Fig. 8. Cyclic monomers providing polyesters via lipase catalysis...

Ring-opening polymerization of a-methyl-substituted medium-size lactones, a-methyl-y-valerolactone and a-methyl-c-caprolactone, proceeded by using lipase CA catalyst in bulk [82]. As to (R)- and (S)-3-methyl-4-oxa-6-hexa-nolides (MOHELs), lipase PC induced the polymerization of both isomers. The apparent initial rate of the S-isomer was seven times larger than that of the R-isomer, indicating that the enantioselective polymerization of MOHEL took place through lipase catalysis [83]. 

Lin, C.N. and Tsai, S.W., Dynamic kinetic resolution of suprofen thioester via coupled triocty-lamine and lipase catalysis. Biotechnol. Bioeng., 2000, 69, 31-38. 

Keywords a,co-Alkanediamines, l,4 3,6-Dianhydrohexitols, Aldaric acids, Aldo-nolactones, Aminoalditols, o-Glucitol, Diaminoalditols, D-Mannitol, D-Xyhtol application, Erythritols, Isoidide, Isomannide, Isosorbide, L-Arabinitol, Lipase-catalysis, Polyamides, Polycarbonates, Polyesteramides, Polyesters, Polyethers, Polyureas, Polyurethanes, Super-acid, Tartaric acids... 

Fig. 2 Synthetic routes to procure polyesters using lipase catalysis (a) ROP of cyclic esters, (b) polycondensation of AA-BB monomers, and (c) polycondensation of AB monomers...

Despite the fact that glycolic acid has been successfully used as an acyl donor in esterification reactions with fatty alcohols, there are few reports dealing with the enzymatic ROP of glycolide [139], On the other hand, cyclic diesters based on ethylene glycol have been polymerized successfully by lipase catalysis and afford AA-BB-typepolyesters [140, 141],... 

Lipases belong to the subclass of a/P-hydrolases and their structure and reaction mechanism are well understood. All lipases possess an identical catalytic triad consisting of an aspartate or glutamate, a histidine, and a nucleophilic serine residue [67], The reaction mechanism of CALB is briefly discussed as a typical example of lipase catalysis (Scheme 7). 

The peptide (melittin) was foimd associated to RMs in a single state as opposed to involvement of at least two forms of melittin with Upid in phospholipid vesicles. Folding and dynamics of this peptide in RMs were also investigated In RMs, activity of a-chymotrypsin was imaffected by pressurization while lipase lost its activity at low pressures and regained on depressurization. The use of pressure as a switch for lipase catalysis is discussed Partition coefficients for 11 amino acids, 17 dipeptides and 5 longer peptides in RMs were determined. 

Fatty acids of sugars are potentially useful and fully green nonionic surfactants, but the lipase-mediated esterification of carbohydrates is hampered by the low solubility of carbohydrates in reaction media that support lipase catalysis in general. Because the monoacylated product (Figure 10.8) is more soluble in traditional solvents than is the starting compound, the former tends to undergo further acylation into a diester. In contrast, the CaLB-catalyzed esterification of glucose with vinyl acetate in the ionic liquid [EMIm][BF4] was completely selective. The reaction became much faster and somewhat less selective when conducted in... 

JM Snyder, JW King, MA Jackson. Analytical supercritical fluid extraction with lipase catalysis conversion of different lipids to methyl esters and effect of moisture. J Am Oil Chem Soc 74 585-588, 1997. 

Lipase catalysis has been used for the synthesis of a poly(e-CL)-monosubsti-tuted first generation dendrimer [169]. 

Scheme 3.1 General scheme for biphasic lipase catalysis [14]...

Ma, L., Persson, M., Aldercreutz, P. 2002. Water activity dependence of lipase catalysis in organic media explains successful transesterification reactions. Enz. Microb. Technol. 31, 1024-1029. 

TABLE 9.1. Comparison between commercial chemical-catalysis and lipase-catalysis methods for biodiesel production. 

Integration of Lipase Catalysis and Product Separation in Supercritical Carbon Dioxide... 

Peracids can also be prepared from reaction of hydrogen peroxide with acyl halides, anhydrides, amides, dialkyl phosphates, N-acylimidazoles, aromatic aldehydes, lipase catalysis and esters (Figure 2.38).100-107... 

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