Abstract
The adsorption of proteins on inorganic surfaces is of fundamental biological importance. Further, biomedical and nanotechnological applications increasingly use interfaces between inorganic material and polypeptides. Yet, the underlying adsorption mechanism of polypeptides on surfaces is not well understood and experimentally difficult to analyze. Therefore, we investigate here the interactions of polypeptides with a gold(111) surface using computational molecular dynamics (MD) simulations with a polarizable gold model in explicit water. Our focus in this paper is the investigation of the interaction of polypeptides with β-sheet folds. First, we concentrate on a β-sheet forming model peptide. Second, we investigate the interactions of two domains with high β-sheet content of the biologically important extracellular matrix protein fibronectin (FN). We find that adsorption occurs in a stepwise mechanism both for the model peptide and the protein. The positively charged amino acid Arg facilitates the initial contact formation between protein and gold surface. Our results suggest that an effective gold-binding surface patch is overall uncharged, but contains Arg for contact initiation. The polypeptides do not unfold on the gold surface within the simulation time. However, for the two FN domains, the relative domain-domain orientation changes. The observation of a very fast and strong adsorption indicates that in a biological matrix, no bare gold surfaces will be present. Hence, the bioactivity of gold surfaces (like bare gold nanoparticles) will critically depend on the history of particle administration and the proteins present during initial contact between gold and biological material. Further, gold particles may act as seeds for protein aggregation. Structural re-organization and protein aggregation are potentially of immunological importance.
Highlights
The interaction of inorganic surfaces with biomolecules like peptides and proteins is central to biotechnology [1], being involved, e.g., in biosensors, biomaterials [2] or the biological use of nanoparticles [3]
These studies showed that the fibrous structure is maintained in typical molecular dynamics (MD) simulation times Fibrillious structures are important for many protein-folding related diseases like Alzheimer or bovine spongiforme encephalopathy (BSE)
Based on simulations of individual amino acids on gold surfaces [15], we proposed earlier that gold surface might stabilize b-sheets, in agreement with the stable individual domain folds observed here
Summary
The interaction of inorganic surfaces with biomolecules like peptides and proteins is central to biotechnology [1], being involved, e.g., in biosensors, biomaterials [2] or the biological use of nanoparticles [3]. The structure of the elastic properties of filaments formed by RAD16II have been investigated by atomistic simulations [25] This peptide has been suggested as a coating to make inorganic surfaces biocompatible, and the interaction of RAD16II fibers with surfaces other than gold (TiO2) has been studied by classical MD simulations [24]. These studies showed that the fibrous structure is maintained in typical MD simulation times Fibrillious structures are important for many protein-folding related diseases like Alzheimer or bovine spongiforme encephalopathy (BSE). For this peptide, which is rich in Arg, we characterize how the Arg side chain can penetrate the water creating a stable initial anchoring points
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
