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Structural variations in nisin associated with different membrane mimicking and pH environments
G A Dykes1, R E Hancock, J W Hastings
1Department of Genetics, University of Natal, Scottsville, South Africa. dykesg@gene.unp.ac.za
Biochemical and Biophysical Research Communications
|July 2, 1998
Summary
Nisin, an antimicrobial peptide, changes structure in membrane environments. At pH 6 and above, it forms beta-turns, potentially affecting its interaction with cell membranes.
Area of Science:
- Biochemistry
- Structural Biology
- Microbiology
Background:
- Nisin is a membrane-active antimicrobial peptide.
- It contains unusual dehydrated amino acid residues.
- Understanding its structure is key to its function.
Purpose of the Study:
- To investigate the secondary structure of nisin.
- To determine structural changes in different environments (aqueous, membrane-mimicking).
- To explore the influence of pH on nisin's structure.
Main Methods:
- Circular dichroism spectroscopy was employed.
- Nisin's structure was analyzed in aqueous solutions.
- Structural changes were observed in liposomes and at varying pH levels.
Main Results:
- In aqueous solution, nisin exists as a random coil.
- In liposomes and at pH 6+, nisin exhibits beta-turn formation.
- Spectral data showed characteristic peaks at 195 nm and 190 nm.
Conclusions:
- Nisin undergoes significant structural changes in membrane-mimicking environments.
- The formation of beta-turns at higher pH may reduce nisin's membrane interaction site availability.
- This pH-dependent structural shift could influence nisin's antimicrobial activity.