Evidence for selective hydrolysis of aliphatic copolyesters induced by lipase catalysis.
High molar mass random poly(butylene succinate-co-butylene sebacate), P(BS-co-BSe), and poly(butylene succinate-co-butylene adipate), P(BS-co-BA), with different composition, were synthesized and subjected to enzymatic hydrolysis by Lipase from Mucor miehei or from Rhizopus arrhizus. The enzymatic hydrolysis of P(BS-co-BSe)s and P(BS-co-BA)s films produced a mixture of water-soluble monomers and co-oligomers that were separated and identified by on-line high performance liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS). Optimization of the HPLC analysis allowed the separation of isobar co-oligomers, differing only for the co-monomers sequence. Oligomers with the same monomer composition and molar mass but different sequence were identified by HPLC/ESI-MS-MS on-line analysis. The results obtained show a preferential hydrolytic cleavage induced by the lipases used. In particular, these enzymes prefer cleaving sebacic ester bonds in P(BS-co-BSe) copolymers, whereas succinic ester bonds appear to be hydrolyzed faster than adipic ester bonds in P(BS-co-BA) copolyesters. 1H NMR analysis further substantiates these findings. The primary products generated by lipase hydrolysis of polyester films underwent further degradation at longer reaction times. The HPLC/ESI-MS analysis of these mixtures at various times provided the first evidence that lipase catalysis is active also in water solution, a hydrophobic effect induced by the aliphatic units of these polyesters.
Istituto di Chimica e Tecnologia dei Polimeri, Consiglio Nazionale delle Ricerche, Viale A Doria 6, 95125 Catania, Italy.
Paola
P
Rizzarelli
Giuseppe
G
Impallomeni
Giorgio
G
Montaudo
D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D006868:Hydrolysis; D008049:Lipase / Q000737:chemistry* / Q000378:metabolism*; D009089:Mucor / Q000201:enzymology; D011091:Polyesters / Q000737:chemistry* / Q000378:metabolism*; D012233:Rhizopus / Q000201:enzymology; D021241:Spectrometry, Mass, Electrospray Ionization
D011091:Polyesters; D008049:Lipase