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Appl. Environ. Microbiol., Aug 1995, 2873-2878, Vol 61, No. 8
HS Rollema, OP Kuipers, P Both, WM de Vos and RJ Siezen
Nisin is a 3.4-kDa antimicrobial peptide that, as a result of
posttranslational modifications, contains unsaturated amino acids and
lanthionine residues. It is applied as a preservative in various food
products. The solubility and stability of nisin and nisin mutants have been
studied. It is demonstrated that nisin mutants can be produced with
improved functional properties. The solubility of nisin A is highest at low
pH values and gradually decreases by almost 2 orders of magnitude when the
pH of the solution exceeds a value of 7. At low pH, nisin Z exhibits a
decreased solubility relative to that of nisin A; at neutral and higher pH
values, the solubilities of both variants are comparable. Two mutants of
nisin Z, which contain lysyl residues at positions 27 and 31, respectively,
instead of Asn-27 and His-31, were produced with the aim of reaching higher
solubility at neutral pH. Both mutants were purified to homogeneity, and
their structures were confirmed by one- and two-dimensional 1H nuclear
magnetic resonance. Their antimicrobial activities were found to be similar
to that of nisin Z, whereas their solubilities at pH 7 increased by factors
of 4 and 7, respectively. The chemical stability of nisin A was studied in
the pH range of 2 to 8 and at a 20, 37, and 75 degrees C. Optimal stability
was observed at pH 3.0. Nisin Z showed a behavior similar to that of nisin
A. A mutant containing dehydrobutyrine at position 5 instead of
dehydroalanine had lower activity but was significantly more resistant to
acid-catalyzed chemical degradation than wild-type nisin Z.
Copyright © 1995, American Society for Microbiology
Improvement of solubility and stability of the antimicrobial peptide nisin by protein engineering
Department of Biophysical Chemistry, Netherlands Institute for Dairy Research (NIZO), Ede.
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