Activity and stability of immobilized penicillin amidase at low pH values

Juliana S. Ferreira, Adrie J.J. Straathof, Telma T. Franco, Luuk A.M. Van Der Wielen

Research output: Contribution to journalArticlepeer-review

Abstract

Penicillin amidase is being applied widely in the production of semi-synthetic β-lactam antibiotics. Usually the processes are at pH 7-8, but for many new applications the range of pH 3-6 is of interest too. Therefore, we studied the activity of penicillin amidase at 25°C in potassium phosphate buffer of pH 3.7-9, as well as its stability in potassium phosphate buffer of pH 3-6. At each pH, the enzyme was stable during at least 32 days. On the other hand, immobilized penicillin amidase incubated in butyl acetate lost its stability, showing after 32 days a decrease of 52% in relation to its initial enzymatic activity value. In phosphate buffer, the enzyme showed the highest activity at pH 8-9. A gradual decrease to about 20% of this activity occurred when the pH was decreased to 3.7. At even lower pH, the enzyme activity could not be determined with the assay that was used due to a very low stability of penicillin G (PenG). The course of penicillin G conversion and 6-aminopenicillanic acid (APA) production, during enzymatic hydrolysis at pH 4, could be quantitatively described by a simple model when the thermodynamic equilibrium of the hydrolysis was taken into account.

Original languageEnglish
Pages (from-to)29-35
Number of pages7
JournalJournal of Molecular Catalysis B: Enzymatic
Volume27
Issue number1
DOIs
Publication statusPublished - 2 Jan 2004
Externally publishedYes

Keywords

  • Immobilized enzyme
  • Penicillin acylase
  • Penicillin G hydrolysis
  • pH optimization
  • Two-phase reaction

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