Adsorption of peptides (A3, Flg, Pd2, Pd4) on gold and palladium surfaces by a coarse-grained Monte Carlo simulation

Monte Carlo simulations are performed to study adsorption and desorption of coarse-grained peptide chains on generic gold and palladium surfaces in the presence of solvent. The atomistic structural details are ignored within the amino acid residues; however, their specificity and hydrophobicity are incorporated via an interaction matrix guided by atomistic simulation. Adsorption probabilities of the peptides A3, Flg, Pd2, Pd4, Gly10, Pro10 on gold and palladium surfaces are studied via analysis of the mobility of each residue, the interaction energy with the surface, profiles of the proximity to the surface, the radius of gyration, and comparisons to homopolymers. In contrast to the desorption of Gly10 and Pro10 (with faster global dynamics), peptides Pd2, Pd4, Flg, and A3 exhibit various degrees of adsorption on gold and palladium surfaces (with relatively slower dynamics). Adsorption on both gold and palladium occurs through aromatic anchoring residues Tyr2 and Phe12 in A3, Tyr2 in Flg, Phe2, His10 and His12 in Pd2, and His6 and His11 in Pd4. A lower (more negative) surface-interaction energy of these residues and lower mobility on palladium lead us to conclude that they are slightly more likely to be adsorbed on palladium surfaces than on gold