Interactions between lipid-free apolipoprotein-AI and a lipopeptide incorporating the RGDS cell adhesion motif

Castelletto, V., Hamley, I. ORCID: https://orcid.org/0000-0002-4549-0926, Reza, M. and Ruokolainen, J. (2015) Interactions between lipid-free apolipoprotein-AI and a lipopeptide incorporating the RGDS cell adhesion motif. Nanoscale, 7 (1). pp. 171-178. ISSN 2040-3364 doi: 10.1039/c4nr05072j

Abstract/Summary

The interaction of a designed bioactive lipopeptide C16-GGGRGDS, comprising a hexadecyl lipid chain attached to a functional heptapeptide, with the lipid-free apoliprotein, Apo-AI, is examined. This apolipoprotein is a major component of high density lipoprotein and it is involved in lipid metabolism and may serve as a biomarker for cardiovascular disease and Alzheimers’ disease. We find via isothermal titration calorimetry that binding between the lipopeptide and Apo-AI occurs up to a saturation condition, just above equimolar for a 10.7 μM concentration of Apo-AI. A similar value is obtained from circular dichroism spectroscopy, which probes the reduction in α-helical secondary structure of Apo-AI upon addition of C16-GGGRGDS. Electron microscopy images show a persistence of fibrillar structures due to self-assembly of C16-GGGRGDS in mixtures with Apo-AI above the saturation binding condition. A small fraction of spheroidal or possibly “nanodisc” structures was observed. Small-angle X-ray scattering (SAXS) data for Apo-AI can be fitted using a published crystal structure of the Apo-AI dimer. The SAXS data for the lipopeptide/ Apo-AI mixtures above the saturation binding conditions can be fitted to the contribution from fibrillar structures coexisting with flat discs corresponding to Apo-AI/lipopeptide aggregates.

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Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/39087
Identification Number/DOI	10.1039/c4nr05072j
Refereed	Yes
Divisions	Interdisciplinary centres and themes > Chemical Analysis Facility (CAF) Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
Additional Information	The full text of this article is freely available via PMC using the link supplied in Related URLs
Publisher	The Royal Society of Chemistry
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