Structure and lipid interactions of an anti-inflammatory and anti-atherogenic 10-residue class G(*) apolipoprotein J peptide using solution NMR.
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.
The Atherosclerosis Research Unit, Department of Medicine, UAB Medical Center, Birmingham, AL 35294, USA. vmishra@uab.edu
Vinod K
VK
Mishra
Mayakonda N
MN
Palgunachari
Jason S
JS
Hudson
Ronald
R
Shin
Tamara D
TD
Keenum
N Rama
NR
Krishna
G M
GM
Anantharamaiah
D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D001703:Biophysics / Q000379:methods; D002151:Calorimetry / Q000379:methods; D002626:Chemistry, Pharmaceutical / Q000379:methods; D002942:Circular Dichroism / Q000379:methods; D051152:Clusterin / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008823:Micelles; D010455:Peptides / Q000737:chemistry; D010767:Phosphorylcholine / Q000031:analogs & derivatives / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D013816:Thermodynamics
D000893:Anti-Inflammatory Agents; D051152:Clusterin; D008055:Lipids; D008823:Micelles; D010455:Peptides; D010767:Phosphorylcholine; C028810:dodecylphosphocholine