Interaction of 18-residue peptides derived from amphipathic helical segments of globular proteins with model membranes |
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Authors: | Chandrasekaran Sivakamasundari Ramakrishnan Nagaraj |
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Institution: | (1) Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research (CSIR), Uppal Road, Hyderabad, 500 007, India |
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Abstract: | We investigated the interaction of six 18-residue peptides derived from amphipathic helical segments of globular proteins
with model membranes. The net charge of the peptides at neutral pH varies from −1 to +6. Circular dichroism spectra indicate
that peptides with a high net positive charge tend to fold into a helical conformation in the presence of negatively charged
lipid vesicles. In helical conformation, their average hydrophobic moment and hydrophobicity would render them surface-active.
The composition of amino acids on the polar face of the helix in the peptides is considerably different. The peptides show
variations in their ability to permeabilise zwitterionic and anionic lipid vesicles. Whereas increased net positive charge
favours greater permeabilisation, the distribution of charged residues in the polar face also plays a role in determining
membrane activity. The distribution of amino acids in the polar face of the helix in the peptides that were investigated do
not fall into the canonical classes described. Amphipathic helices, which are part of proteins, with a pattern of amino acid
distribution different from those observed in class L, A and others, could help in providing newer insights into peptide-membrane
interactions. |
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Keywords: | Amphipathic helical peptides average hydrophobicity hydrophobic moment membrane-permeabilisation model membranes |
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