US EPA

4117092 

Journal Article 

Activity and stability of immobilized penicillin amidase at low pH values 

Ferreira, JS; Straathof, AJJ; Franco, TT; van der Wielen, LAM 

2004 

Yes 

Journal of Molecular Catalysis B: Enzymatic
ISSN: 1381-1177 

27 

1 

29-35 

10.1016/j.molcatb.2003.09.003 

WOS:000188379700005 

Penicillin amidase is being applied widely in the production of semi-synthetic beta-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 degreesC 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. (C) 2003 Elsevier B.V. All rights reserved. 

penicillin acylase; immobilized enzyme; two-phase reaction; penicillin G hydrolysis; pH optimization