Surface-induced conformational switching in amphiphilic peptide segments of apolipoproteins B and E and model peptides†

The conformational and surface-binding properties of a synthetic peptide corresponding to Tyr-apolipoprotein B-100(1000–1016) amide, SP-4, which was previously shown to mimic the focal accumulation pattern of LDL on the healing de-endothelialized rabbit aorta [Shih et al. (1990) Proc. Natl. Acad. Sci. USA 87 , 1436–1440], have been investigated. SP-4 behaves as an amphiphilic α-helical peptide at the air-water interface and bound to siliconized quartz slides. However, its N^α-acetylated analogue formed β-sheet structures at the air-water interface. Nonhomologous peptide models of SP-4 also exhibited mixed α-helical and β-sheet surface-binding behavior. Peptides corresponding to the cationic apolipoprotein (apo) B/E receptor binding regions of apoE (SP-2) and apoB (SP-11) were also studied. SP-2 behaved as an amphiphilic α helix, but, surprisingly, SP-11 formed surface-induced β-sheets. These results demonstrate that all of the peptides studied have surface-binding properties, and suggest further that either α-helical or β-sheet peptide structures may determine the binding of LDL to the arterial wall or the apoB/E receptor.