title: Thermal inactivation of immobilized penicillin acylase in the presence of substrate and products.
abstract: Inactivation of immobilized penicillin acylase has been studied in the presence of substrate (penicillin G) and products (phenylacetic acid and 6-aminopenicillanic acid), under the hypothesis that substances which interact with the enzyme molecule during catalysis will have an effect on enzyme stability. The kinetics of immobilized penicillin acylase inactivation was a multistage process, decay constants being evaluated for the free-enzyme and enzyme complexes, from whose values modulation factors were determined for the effectors in each enzyme complex at each stage. 6-Aminopenicillanic acid and penicillin G stabilized the enzyme in the first stage of decay. Modulation factors in that stage were 0.96 for penicillin G and 0.98 for 6-aminopenicillanic acid. Phenylacetic acid increased the rate of inactivation in both stages, modulating factors being -2.31 and -2.23, respectively. Modulation factors influence enzyme performance in a reactor and are useful parameters for a proper evaluation.
authors.affiliation: School of Biochemical Engineering, Universidad Católica de Valparaíso, PO Box 4059, Valparaíso, Chile.
authors.forename: A
authors.initials: A
authors.lastname: Illanes
authors.forename: C
authors.initials: C
authors.lastname: Altamirano
authors.forename: M E
authors.initials: ME
authors.lastname: Zuñiga