SERS, Molecular Dynamics and Molecular Orbital Studies of the MRKDV Peptide on Silver and Membrane Surfaces

Abstract

The MRKDV peptide, structurally associated 9 with an immunomodulatory protein, was studied using surface 10 enhanced Raman scattering (SERS), molecular dynamics (MD) 11 simulations, and quantum chemical calculations. The SERS 12 spectrum of the MRKDV peptide adsorbed on the silver surface 13 is dominated by signals coming from the guanidinium moiety of 14 the arginine amino acid (R). Guanidinium is the intrinsic probe 15 that drives the orientation of the peptide onto the silver surface. 16 Molecular mechanics and extended H€uckel calculations of a 17 model of MRKDV interacting with a silver surface support the 18 experimental results. MD calculations representing the evolution of the peptide toward a model membrane were also performed. 19 The guanidinium moiety interacts with the phospholipidic membrane surface. A hydrophobic C-terminal modification favors the 20 peptide membrane affinity.