RESUMO
Penicillin G acylase (PGA) from Kluyvera citrophila immobilized on Amberzyml was used for enantioselective hydrolysis of N-phenylacetylated-DL-tert-leucine (N-Phac-DL-Tle) to produce L-tert-leucine (L-Tle). The effects of various organic cosolvents on hydrolysis of N-Phac-DL-Tle have been investigated in aqueous-cosolvent medium. It was founded that the rate of PGA-catalyzed reaction was significantly affected by the presence of 2% (v/v) organic cosolvent concentration. The initial rate fell with increasing logP of the cosolvent, but for logP values less than -0.24 the rate was faster than in purely aqueous medium. Additionally, the relative rate increases with the increase of dielectric constant (epsilon) of organic cosolvents. The yields of L-Tle in all aqueous-cosolvent systems were above 95% with the enantiomeric excess (ee) of >99%.
Assuntos
Kluyvera/enzimologia , Compostos Orgânicos/química , Penicilina Amidase/química , Solventes/química , Valina/análogos & derivados , Ativação Enzimática , Enzimas Imobilizadas/química , Cinética , Leucina/análogos & derivados , Valina/químicaRESUMO
Several ionic liquids were used as reaction media for penicillin G acylase catalysis. In all the assayed ionic liquids, [bmim]PF6 proved good media for PGA-catalyzed hydrolysis. A novel [bmim]PF6/water two-phase system is provided for 6-aminopenicillanic acid (APA) production, which will be more benefical than aquous batch systems used widely in industrial production of APA.
Assuntos
Escherichia coli/enzimologia , Líquidos Iônicos/química , Penicilina Amidase/química , Penicilina G/química , Catálise , Ativação Enzimática , Estabilidade Enzimática , Hidrólise , Especificidade por SubstratoRESUMO
Penicillin G acylase, from Kluyvera citrophila, was used in kinetic resolution of DL-tert-leucine. N-phenylacetylated-DL-tert-leucine, chemically synthesized from DL-tert-leucine, was enantioselctively hydrolyzed by penicillin G acylase to obtain L-tert-leucine, D-tert-leucine was prepared by acid-catalyzed hydrolysis of the remaining substrate. The total yields of D-tert-leucine and L-tert-leucine are 80.6% and 83.1%, respectively. The enantiomeric excess of the two products, D-tert-leucine and L-tert-leucine, are 98.5% and 99%. This is a practical way for the preparation of D-tert-leucine and L-tert-leucine.
Assuntos
Leucina/análogos & derivados , Leucina/síntese química , Penicilina Amidase/metabolismo , Catálise , Concentração de Íons de Hidrogênio , Hidrólise , Kluyvera/enzimologia , Leucina/química , Estrutura Molecular , Rotação Ocular , Penicilina G/metabolismoRESUMO
L-Ascorbyl oleate and L-ascorbyl linoleate were synthesized by an immobilized lipase from Candida antarctica with yields of 38% and 44%, respectively. L-Ascorbyl oleate was stable in sterile culture medium over 12 h at 37 degrees C but L-ascorbyl linoleate degraded by 17%. Ascorbyl oleate had a better protective effect on human umbilical cord vein endothelial cells treated with H2O2 than of L-ascorbic acid-2-phosphate-6-palmitate (Asc2P6P).