Molecular Dynamics Simulations of C-Terminal Decapeptide of Gastrin-Releasing Peptide in DMPC Bilayers: Structure, Stability and Orientation of the Peptide Hormone Within the Bilayers

Gastrin-releasing peptide (GRP) is a member of bombesin-like peptides and bombesin and neuromedin B are other members of this family. They act on receptors that belong to the GPCR superfamily and exert important physiological functions upon binding to their receptors. The biologically active C-terminal decapeptide of GRP (GRP10) was studied in explicit DMPC bilayers using molecular dynamics simulations. In the initial conformation, the peptide was placed perpendicular to the membrane plane and the peptide-membrane complex with ∼20,000 atoms was simulated for a period of 8 ns. After a 5 ns simulation, GRP10 adopted a tilted orientation and the tilt angle with respect to the bilayer normal was ∼60°. Analysis of the interactions of individual residues indicated the role of histidine residues in maintaining a tilted orientation.