title: [Studies on enzymatic synthesis of cephalexin by immobilized penicillin acylase by polyacrylonitrile fibres].
abstract: The extracellular penicillin acylase from Bacillus megaterium was immobilized by coupling to derivatives of polyacrylonitrile fibres. The apparent activity of the immobilized enzyme was about 153 U/g (wet weight). The optimal pH and temperature were 6.5 and 40 degrees C for synthesis of cephalexin by penicillin acylase, respectively. Whe the concentration of 7-ADCA was 4% and the ratio of PGME and 7-ADCA and 1:2, the average velocity of synthesis reaction was highest. The optimal supplied amount of immobilized penicillin acylase was 1.125 g/g 7-ADCA.. The apparent Michaelis constant for 7-ADCA was 0.162 mol/L and for PGME was 0.364 mol/L, Vmax was 0.0462 mol.L-1.min-1 at 30 degrees C and pH6.5. The remained activity was about 83.9% after operating 50 times.
authors.affiliation: Institute of Microbiology, Chinese Academy of Sciences, Beijing 100080, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.forename: Hui
authors.initials: H
authors.lastname: Han
authors.forename: Guanzhu
authors.initials: G
authors.lastname: Xu
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D001410:Bacillus megaterium / Q000201:enzymology*; D002506:Cephalexin / Q000138:chemical synthesis*; D004800:Enzymes, Immobilized / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D010399:Penicillin Amidase / Q000302:isolation & purification / Q000378:metabolism*; D013696:Temperature
chemical_list: D000180:Acrylic Resins; D004800:Enzymes, Immobilized; C010504:polyacrylonitrile; D010399:Penicillin Amidase; D002506:Cephalexin