The conformational space of a flexible amino acid at metallic surfaces

Dmitrii Maksimov,Mariana Rossi,Carsten Baldauf

doi:10.1002/qua.26369

Abstract

AbstractIn interfaces between inorganic and biological materials relevant for technological applications, the general challenge of structure determination is exacerbated by the high flexibility of bioorganic components, chemical bonding, and charge rearrangement at the interface. In this paper, we investigate a chemically complex building block, namely, the arginine (Arg) amino acid interfaced with Cu, Ag, and Au (111) surfaces. We investigate how the environment changes the accessible conformational space of this amino acid by building and analyzing a database of thousands of structures optimized with the Perdew‐Burke‐Ernzerhof (PBE) functional, including screened pairwise van der Waals interactions. When in contact with metallic surfaces, the accessible space for Arg is dramatically reduced, while the one for Arg‐H+ is instead increased if compared to the gas phase. This is explained by the formation of strong bonds between Arg and the surfaces and by their absence and charge screening on Arg‐H+ upon adsorption. We also observe protonation‐dependent stereoselective binding of the amino acid to the metal surfaces: Arg adsorbs with its chiral CαH center pointing H away from the surfaces, while Arg‐H+ adsorbs with H pointing toward the surface.

Highlights

The organic-inorganic interfaces formed between peptides and surfaces are of interest to diverse fields such as medicine, optoelectronics, and energy storage.[1,2,3,4,5,6,7,8,9,10] Amino acids and their oligomers—that is, peptides—are interesting materials because they are naturally biocompatible and offer a rich functional space already at the amino acid level, which can be extended by the combinatorial increase of molecular motifs available through the peptide bond formation
We investigate a chemically complex building block, namely, the arginine (Arg) amino acid interfaced with Cu, Ag, and Au (111) surfaces
We focused on structural aspects of the adsorbed molecules and the most prominent bonds the molecules make with the metallic surfaces

Summary

Introduction

The organic-inorganic interfaces formed between peptides and surfaces are of interest to diverse fields such as medicine, optoelectronics, and energy storage.[1,2,3,4,5,6,7,8,9,10] Amino acids and their oligomers—that is, peptides—are interesting materials because they are naturally biocompatible and offer a rich functional space already at the amino acid level, which can be extended by the combinatorial increase of molecular motifs available through the peptide bond formation In these setups, the inorganic component offers a platform to immobilize and template the bioorganic counterpart, as well as to record electronic signals from interactions or reactions.

Methods

Results

Conclusion