Interactions between lipid-free apolipoprotein-AI and a lipopeptide incorporating the RGDS cell adhesion motif. Issue 1 (14th November 2014)

• Record Type: Journal Article
• Authors: Castelletto, V.; Hamley, I. W.; Reza, M.; Ruokolainen, J.
• Is Part Of: Nanoscale. Volume 7:Issue 1(2015)
• Page Start: 171
• Page End: 178
• Publication Date: 2014-11-14
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/c4nr05072j
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : Interactions of the bioactive lipopeptide C16 -GGGRGDS, with the lipid-free apoliprotein, Apo-AI. Abstract : 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.