NMR Study on the Binding of Neuropeptide Achatin-I to Phospholipid Bilayer: The Equilibrium, Location, and Peptide Conformation

Abstract

Molecular mechanism of the binding of neuropeptide achatin-I (Gly-D-Phe-Ala-Asp) to large unilamellar vesicles of zwitterionic egg-yolk phosphatidylcholine (EPC) was investigated by means of natural-abundance (13)C and high-resolution (of 0.01 Hz order) (1)H NMR spectroscopy. The binding equilibrium was found to be sensitive to the ionization state of the N-terminal NH(3)(+) group in achatin-I; the de-ionization of NH(3)(+) decreases the bound fraction of the peptide from approximately 15% to nearly none. The electrostatic attraction between the N-terminal positive NH(3)(+) group and the negative PO(4)(-) group in the EPC headgroup plays an important role in controlling the equilibrium. Analysis of the (13)C chemical shifts (delta) of EPC showed that the binding location of the peptide within the bilayer is the polar region between the glycerol and ester groups. The binding caused upfield changes Delta delta of the (13)C resonance for almost all the carbon sites in achatin-I. The changes Delta delta for the ionic Asp at the C-terminus are more than five times as large as those for the other residues. The drastic changes for Asp result from the dehydration of the ionic CO(2)(-) groups, which are strongly hydrated by electrostatic interactions in bulk water. The side-chain conformational equilibria of the aromatic d-Phe and ionic Asp residues were both affected by the binding, and the induced changes in the equilibria appear to reflect the peptide-lipid hydrophobic interactions.

Location, Structure, and Dynamics of the Synthetic Cannabinoid Ligand CP-55,940 in Lipid Bilayers

“…2. The reduction Biophysical Journal 96 (12) 4916-4924 of order takes place along the entire chain. The same trend was observed regardless of the temperature in the investigated range of 5-45 C (see Fig.…”

“…A similar diffusion-controlled mechanism of receptor approach was also proposed for binding between amphipathic neuropeptides and GPCRs (10). These peptides possess significant affinity for membranes, and molecular details of the peptide-lipid interactions are being elucidated (10)(11)(12)(13). The binding crevice for ligands of cannabinoid receptors is expected to be located among transmembrane helices III, V, VI, and VII near the extracellular face of the receptor (14), as was recently found for the crystal structures of the b 2 -adrenergic receptor (15) and the human A 2A adenosine receptor (16).…”

“…The temperature inside the spinning rotor was 17 C, which was calibrated by recording the proton spectra of 1-stearoyl-2-oleoyl-sn-glyero-3-phosphocholine (SOPC) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) as a function of temperature to detect the gel-to-liquid crystalline phase transition at 6.6 C (32) and 23.5 C (33), respectively. The temperature was controlled to 50.1 C. Biophysical Journal 96 (12) 4916-4924…”

Induction of raft‐like domains by a myristoylated NAP‐22 peptide and its Tyr mutant

“…We suggest that in addition to ring‐current effects there are peptide‐induced changes in lipid packing and interaction with water. It is known that dehydration will cause an upfield chemical shift of 13 C resonances [20].…”

Mobility and location of anesthetics in lipid bilayer membranes by high-resolution, high-field-gradient NMR

“…The high-resolution natural-abundance 13 C NMR method can distinguish the individual carbon atom site of the bilayer without labeling [2][3][4][5][6]. Utilizing the site-selective 13 C NMR, we specify the preferential location of anesthetics in membranes at the molecular level.…”