# Studies on the aggregation and possible channel formation in membranes of a cyclic hexapeptide, cyclo $(d-Ala-l-Pro-l-Ala)_2$

Ramesh, J and Ghosh, JK and Swaminathan, CP and Ramasamy, P and Surolia, A and Sikdar, SK and Easwaran, KRK (2003) Studies on the aggregation and possible channel formation in membranes of a cyclic hexapeptide, cyclo $(d-Ala-l-Pro-l-Ala)_2$. In: Journal of Peptide Research, 61 (2). pp. 63-70.

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## Abstract

The interaction of zwitterionic lipid DMPC and DPPC with cyclic hexapeptide, cyclo $(d-Ala-l-Pro-l-Ala)_2$ was studied using circular dichroism (CD) and differential scanning calorimetry (DSC). Preliminary membrane conductance results showed that the peptide has a tendency to form channels inside the lipid bilayer. CD studies indicated that as the lipid/peptide (L/P) ratio (DMPC/peptide) was increased, the magnitude of the negative CD band having a \lambda max around 200 nm decreased. At a L/P ratio of 210:1, this band disappeared completely, indicating dramatic conformational changes in the peptide on interaction with the lipid bilayer. Reduction of the phase transition temperature and the maximum heat capacity of the lipid bilayer (DPPC) for gel-to-liquid crystalline phase transition indicates a strong interaction of the peptide with the lipid bilayer.

Item Type: Journal Article The Copyright belongs to Blackwell. Division of Biological Sciences > Molecular Biophysics Unit Nagaraj Vaidya 03 Jun 2006 27 Aug 2008 12:10 http://eprints.iisc.ac.in/id/eprint/7507