Interfacial properties of amphipathic β strand consensus peptides of apolipoprotein B at oil/water interfaces

Abstract

The region between residues 968 and 1882 of apolipoprotein B (apoB-21 to apoB-41) is rich in amphipathic β strands (AβSs) and promotes the assembly of primordial triacylglyceride (TAG)-rich lipoproteins. To understand the importance of AβS in recruiting TAG, the interfacial properties of two AβS consensus peptides, P12 and P27, were studied at dodecane/water (DD/W) and triolein/water (TO/W) interfaces. P12 (acetyl-LSLSLNADLRLK-amide) and P27 (acetyl-LSLSLNADLRLKNGNLSLSLNADLRLK-amide), when added into the aqueous phase surrounding a suspended oil drop (dodecane or triolein), decreased the interfacial tension (γ) in a concentration-dependent manner. At the DD/W interface, 1 × 10−5 M P12 decreased γ to ∼20 mN/m and 6.6 × 10−6 M P27 decreased γ to ∼13 mN/m. At the TO/W interface, 1.5 × 10−5 M P12 decreased γ to ∼14 mN/m and 9.0 × 10−6 M P27 decreased γ to ∼12 mN/m. The surface area of both peptides was between 11.2 and 15.1 Å2 per residue, consistent with β sheets lying flat on DD/W and TO/W interfaces. P12 and P27 are almost purely elastic on DD/W, TO/W, and air/water interfaces. When P12 and P27 were compressed beyond the equilibrium γ to as low as 4 mN/m, they could not be readily desorbed from either interface.These properties probably help in assembling nascent TAG-rich lipoproteins, and AβS may anchor apoB to β lipoproteins.

Keywords

• dodecane/water interface
• triolein/water interface
• air/water interface
• low density lipoprotein