Structure of optimized GRP sheet and initial position of asparagine before molecular dynamics.
Optimized structure of phenylalanine on GRP in vacuum: (a) and (b) uncapped, and (c) and (d) capped.
Adsorption energy of capped and uncapped amino acids to GRP in vacuum. The amino acids are arranged according to their hydrophobicity index (from most hydrophobic to most hydrophilic). In most cases, the adsorption energies for the capped amino acids are higher in comparison to uncapped due to a larger number of atoms in the residue that contribute to the dispersion interaction with the GRP.
Adsorption energy of capped amino acids to GRP in water and in vacuum. The adsorption energies for the capped amino acids in water are significantly lower than that in vacuum because of the desolvation effect presented in aqueous environment.
The correlation between the amino acid atomic weight and the dispersion (van der Waals) component of the adsorption energy. Results are shown for capped amino acids in water. Larger amino acids exhibit a stronger dispersion interaction with the substrate.
Position of carbon-α atom in leucine (capped/uncapped structure) on GRP sheet in the simulation cell with water. The z-axis is perpendicular to the GRP layer with the origin assigned to the GRP plane. The graph shows that capped leucine adsorbs to the surface and remains in the bound state during the entire simulation time span. In contrast to that, the uncapped version of leucine frequently desorbs from the surface, which indicates a weaker adhesion to the substrate. This trend was also observed for the remaining 19 amino acids studied here.
Adsorption energy of capped and uncapped amino acids to GRP in water. The uncapped amino acids are unable to bind permanently to the surface of GRP because of the stronger interaction (attractive Coulomb and dispersion interaction of the amino acid) with water competing with the amino-acid–GRP interaction.
Adsorption energy (eV) of amino acids (capped and uncapped) and water molecule on GRP sheet in vacuum calculated using empirical force fields.
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