TY - JOUR
T1 - Activity and stability of immobilized penicillin amidase at low pH values
AU - Ferreira, Juliana S.
AU - Straathof, Adrie J.J.
AU - Franco, Telma T.
AU - Van Der Wielen, Luuk A.M.
PY - 2004/1/2
Y1 - 2004/1/2
N2 - 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.
AB - 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.
KW - Immobilized enzyme
KW - Penicillin acylase
KW - Penicillin G hydrolysis
KW - pH optimization
KW - Two-phase reaction
UR - http://www.scopus.com/inward/record.url?scp=0346725120&partnerID=8YFLogxK
U2 - 10.1016/j.molcatb.2003.09.003
DO - 10.1016/j.molcatb.2003.09.003
M3 - Article
AN - SCOPUS:0346725120
SN - 1381-1177
VL - 27
SP - 29
EP - 35
JO - Journal of Molecular Catalysis B: Enzymatic
JF - Journal of Molecular Catalysis B: Enzymatic
IS - 1
ER -