Thermal inactivation of immobilized penicillin acylase in the presence of substrate and products

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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.

Original languageEnglish
Pages (from-to)609-616
Number of pages8
JournalBiotechnology and Bioengineering
Issue number6
StatePublished - 20 Jun 1996
Externally publishedYes


  • 6-aminopenicillanic acid
  • enzyme inactivation
  • penicillin acylase
  • product modulation
  • substrate modulation


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