With recent development of enzyme engineering, the use of enzyme in organic solvents is rapidly increasing. The remarkable stereoselectivity and regioselectivity of reaction catalyzed by enzyme were used to resolve ma...With recent development of enzyme engineering, the use of enzyme in organic solvents is rapidly increasing. The remarkable stereoselectivity and regioselectivity of reaction catalyzed by enzyme were used to resolve many racemic alcohols and esters. A number of results have also been reported about the resolution of amino acids in organic solvents. For example, DL-phenylalanine methyl ester was resolved by α-chymotrypsin in toluene/water biphasic system; in fact, this reaction was carried, out in water;transesterification of DL-phenylalanine propyl ester and methanol was catalyzed by α-chymotrypsin in methanol, and the enzyme used was dissolved in water and the展开更多
Porcine pancreas lipase(PPL) immobilized on narrow distributed micron glass beads was employed successfully for ring-opening polymerization of ε-caprolactone(CL).Different polymerization conditions such as enzyme con...Porcine pancreas lipase(PPL) immobilized on narrow distributed micron glass beads was employed successfully for ring-opening polymerization of ε-caprolactone(CL).Different polymerization conditions such as enzyme concentration,reaction temperature and reaction time were studied.The results showed that M_n of the resulting PCL was significantly increased compared with that catalyzed by PPL.Higher temperature and longer reaction time both contributed to gaining PCL with a higher molecular weight,while the yield had almost no change.In addition,for evaluating the recyclibilty of immobilized PPL on narrow distributed micron glass beads for the ring-opening polymerization of CL,we adopted the most severe reaction conditions(180 ℃,(240 h)) in the recycling experiments.It was found that the recovered immobilized PPL could be used again with a compatible high catalytic activity.The highest M_n of 21 300 of PCL could be obtained at a mass fraction of 5.18% of the reused immobilized PPL at 180 ℃ for 240 h,which is the highest M_n of PCL catalyzed by PPL.The excellent recyclability of immobilized PPL on narrow distributed micron glass beads is very helpful to its further industry applications.展开更多
文摘With recent development of enzyme engineering, the use of enzyme in organic solvents is rapidly increasing. The remarkable stereoselectivity and regioselectivity of reaction catalyzed by enzyme were used to resolve many racemic alcohols and esters. A number of results have also been reported about the resolution of amino acids in organic solvents. For example, DL-phenylalanine methyl ester was resolved by α-chymotrypsin in toluene/water biphasic system; in fact, this reaction was carried, out in water;transesterification of DL-phenylalanine propyl ester and methanol was catalyzed by α-chymotrypsin in methanol, and the enzyme used was dissolved in water and the
文摘Porcine pancreas lipase(PPL) immobilized on narrow distributed micron glass beads was employed successfully for ring-opening polymerization of ε-caprolactone(CL).Different polymerization conditions such as enzyme concentration,reaction temperature and reaction time were studied.The results showed that M_n of the resulting PCL was significantly increased compared with that catalyzed by PPL.Higher temperature and longer reaction time both contributed to gaining PCL with a higher molecular weight,while the yield had almost no change.In addition,for evaluating the recyclibilty of immobilized PPL on narrow distributed micron glass beads for the ring-opening polymerization of CL,we adopted the most severe reaction conditions(180 ℃,(240 h)) in the recycling experiments.It was found that the recovered immobilized PPL could be used again with a compatible high catalytic activity.The highest M_n of 21 300 of PCL could be obtained at a mass fraction of 5.18% of the reused immobilized PPL at 180 ℃ for 240 h,which is the highest M_n of PCL catalyzed by PPL.The excellent recyclability of immobilized PPL on narrow distributed micron glass beads is very helpful to its further industry applications.
