Aggregation of a Peptide Antibiotic Alamethicin at the Air#Water Interface and Its Influence on the Viscoelasticity of Phospholipid Monolayers

Krishnaswamy, Rema and Rathee, Vikram and Sood, AK (2008) Aggregation of a Peptide Antibiotic Alamethicin at the Air#Water Interface and Its Influence on the Viscoelasticity of Phospholipid Monolayers. In: Langmuir, 24 (20). pp. 11770-11777.

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Abstract

The aggregation properties of an antibiotic membrane-active peptide alamethicin at the air-water interface have been studied using interfacial rheology and fluorescence microscopy techniques. Fluorescence microscopy of alamethicin monolayers revealed a coexistence of liquid expanded (LE) and solid phases at the surface concentrations studied. Interfacial oscillatory shear measurements on alamethicin monolayers indicate that its viscoelastic properties are determined by the area fraction of the solid domains. The role of zwitterionic phospholipids dioleoylphosphatidyl choline (DOPC) and dioleoylphosphatidyl ethanolamine (DOPE) on the peptide aggregation behavior was also investigated. Fluorescence microscopy of alamethicin/phospholipid monolayers revealed an intermediate phase (I) in addition to the solid and LE phase. In mixed monolayers of phospholipid (L)/alamethicin (P), with increase in L/P, the monolayer transforms from a viscoelastic to a viscous fluid with the increase in area fraction of the intermediate phase. Further, a homogeneous mixing of alamethicin/lipid molecules is observed at L/P > 4. Our studies also confirm that the viscoelasticity of alamethicin/phospholipid monolayers is closely related to the alamethicin/phospholipid interactions at the air-water interface.

Item Type:	Journal Article
Publication:	Langmuir
Publisher:	American Chemical Society
Keywords:	Aggregation of a Peptide Antibiotic Alamethicin;Peptide;Antibiotic;Viscoelasticity;Phospholipid Monolayers;air-water interface;Alamethicin Monolayers;Interfacial Oscillatory Shear on Alamethicin Monolayer;Surface Rheology of Alamethicin;Lipid Monolayers.
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	03 Dec 2008 07:13
Last Modified:	19 Sep 2010 04:52
URI:	http://eprints.iisc.ac.in/id/eprint/16512

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