BioEngineering Research GroupJ. Chem. Technol. Biotechnol., 74, 1110-1116 (1999)
Azevedo, A. M., Fonseca, L. P., Prazeres, D. M. F.
The stability of an oligomeric enzyme, penicillin acylase, was studied in aqueous
media. The enzyme was produced by mutant cells of Escherichia coli ATCC 9637,
extracted from the periplasmic space by osmotic shock and further purified using a
pseudo-affinity adsorption process. Enzyme stabilisation attempts were performed with
salts, alcohols and sugars. The highest levels of retained activity were obtained in the
presence of 15% (w/v) ammonium or sodium sulphate.
A kinetic model was proposed to describe the inactivation of penicillin acylase, taking
into account results obtained in stability assays performed at different temperatures and
with different enzyme concentrations. According to this model, the inactivation of
penicillin acylase involves an intermediary active precursor of the enzyme, formed prior
to dissociation into sub-units.
Keywords: penicillin acylase; oligomeric enzyme; thermostability; stabilisation; deactivation
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