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J Lipid Res. 2013 Jun;54(6):1578-88. doi: 10.1194/jlr.M034462. Epub 2013 Mar 25.

Surface pressure-dependent conformation change of apolipoprotein-derived amphipathic α-helices.

Author information

1
Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA, USA. matthew.mitsche@utsouthwestern.edu

Abstract

Amphipathic α-helices (AαH) are the primary structural motif of exchangeable apolipoproteins. AαHs in exchangeable apolipoproteins adsorb, remodel, and desorb at the surface of plasma lipoproteins in response to changes in their size or composition. A triolein/water (TO/W) interface was used as a model surface to study adsorption and desorption of AαHs at a lipoprotein-like interface. We previously reported that AαH peptides spontaneously adsorb to a TO/W interface, but they only partially desorb from the surface when the excess peptide was removed from the system. This finding suggests that "exchangeable" apolipoproteins are in fact partially exchangeable and only desorb from a surface in response to compression or change in composition. Here, we develop a thermodynamic and kinetic model to describe this phenomenon based on the change in the interfacial pressure (Π) of the C-terminal 46 amino acids of apolipoprotein A-I (C46) at a TO/W interface. This model suggests that apolipoproteins have at least two interfacial conformations that are in a surface concentration and Π-dependent equilibrium. This two-state surface equilibrium model, which is based on experimental data and is consistent with dynamic changes in Π(t), provides insights into the selective metabolism and clearance of plasma lipoproteins and the process of lipoprotein remodeling.

KEYWORDS:

apolipoproteins; lipoprotein remodeling; protein-lipid interactions

PMID:
23528259
PMCID:
PMC3646459
DOI:
10.1194/jlr.M034462
[Indexed for MEDLINE]
Free PMC Article

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