Structure and lipid interactions of an anti-inflammatory and anti-atherogenic 10-residue class G(*) apolipoprotein J peptide using solution NMR.

Academic Article

Abstract

  • The surprising observation that a 10-residue class G(⁎) peptide from apolipoprotein J, [113-122]apoJ, possesses anti-inflammatory and anti-atherogenic properties prompted us to delineate its structural characteristics in the presence of normal and oxidized lipid. Towards this, we have determined high-resolution structure of [113-122]apoJ in solution using nuclear magnetic resonance (NMR) spectroscopy and studied its interaction with lipids, including oxidized lipids, using a number of biophysical methods. Circular dichroism and NMR studies established that in the presence of dodecylphosphocholine (DPC) micelle, this peptide adopts amphipathic α-helical structure. The observed Nuclear Overhauser effects indicate that the amphipathic helical structure of the peptide is stabilized by the N-terminal acetyl and C-terminal amide blocking groups. We used isothermal titration calorimetry to measure binding enthalpy of the peptide with DPC micelle, an oxidized lipid, 1-(palmitoyl)-2-(5-keto-6-octene-dioyl) phosphatidylcholine (KOdiA-PC), and the mixture of these two lipids (5mol% KOdiA-PC in DPC micelle). We find that the peptide binding with DPC micelle is associated with an enthalpy change (-16.75±0.16 Kcal/mol) much larger than that resulting from the binding with KodiA-PC (-3.67±0.13 Kcal/mol). Incorporation of a small amount of KOdiA-PC (5mol%) in DPC micelle also results in the lowering of peptide binding enthalpy (-13.43±0.18 Kcal/mol). These results are consistent with overall negative charge and altered conformational properties of oxidized sn-2 chain of KOdiA-PC. Our results have unambiguously established the amphipathic α-helical structure of [113-122]apoJ peptide in the presence of DPC micelle as well as its ability to bind oxidized lipid. These in vitro results help explain the previously observed anti-inflammatory and anti-atherosclerotic properties of this peptide.
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    Keywords

  • Anti-Inflammatory Agents, Biophysics, Calorimetry, Chemistry, Pharmaceutical, Circular Dichroism, Clusterin, Lipids, Magnetic Resonance Spectroscopy, Micelles, Peptides, Phosphorylcholine, Protein Binding, Protein Conformation, Protein Structure, Secondary, Thermodynamics
  • Digital Object Identifier (doi)

    Authorlist

  • Mishra VK; Palgunachari MN; Hudson JS; Shin R; Keenum TD; Krishna NR; Anantharamaiah GM
  • Start Page

  • 498
  • End Page

  • 507
  • Volume

  • 1808
  • Issue

  • 1