Quantitatively Identifying the Roles of Interfacial Water and Solid Surface in Governing Peptide Adsorption

Abstract

Understanding the molecular mechanism of protein adsorption on solids is critical to their applications in materials synthesis and tissue engineering. Although the water phase at the surface/water interface has been recognized as three types: bulk water, intermediate water phase and surface-bound water layers, the roles of the water and surface in determining the protein adsorption are not clearly identified, particularly at the quantitative level. Herein, we provide a methodology involving the combination of microsecond strengthen sampling simulation and force integration to quantitatively characterize the water-induced contribution and the peptide-surface interactions into the adsorption free energy. Using hydroxyapatite and graphene surfaces as examples, we demonstrate how the distinct interfacial features dominate the delicate force balance between these two thermodynamics parameters, leading to surface preference/resistance to peptide adsorption. Specifically, the water layer provides sustained repelling force against peptide adsorption, as indicated by a monotonic increase in the water-induced free energy profile, whereas the contribution from the surface-peptide interactions is thermodynamically favorable to peptide adsorptions. More importantly, the revealed adsorption mechanism is critically dictated by the distribution of water phase, which plays a crucial role in establishing the force balance between the interactions of the peptide with the water layer and the surface. For the HAP surface, the charged peptide exhibits strong binding affinity to the surface, due to the controlling contribution of peptide-surface interaction in the intermediate water phase. The surface-bound water layers are observed as the origin of bioresistance of solid surfaces toward the adsorption of charge-neutral peptides. The preferred peptide adsorption on the graphene, however, is dominated by the surface-induced component at the water layers adjacent to the surface. Our results further elucidate that the intermediate water phase significantly shortens the effective range of the surface dispersion force, in contrast to the observation on the hydrophilic surface.

Insights into the conformation changes of SARS-CoV-2 spike receptor-binding domain on graphene

“…All simulations were exceuted with Gromacs package 5.1.4 [40] , [41] . The interaction between RBD and graphene was simulated by CHARMM36, which is widely used to describe the molecular dynamics behavior of proteins [42] , [43] , [44] , [45] , [46] . The C atoms in graphene were regarded as uncharged Lennard-Jones particles.…”

Entropy–Enthalpy Compensation in Peptide Adsorption on Solid Surfaces: Dependence on Surface Hydration

“…22,24−26 and water molecules are involved at the interface, entropy could be the vital thermodynamic factor dominating interfacial adsorption. 27 The disruption of the surface-bound water layers from the adsorption leads to entropy gain since the water molecules previously bound to the surface are released into the bulk solution. 28 The surface-restraining effect on the adsorbate results in the entropic penalty due to its loss of configuration freedoms (translation and rotation).…”

Adsorption of amino acids on graphene: assessment of current force fields

“…Graphene is described by the Lennard-Jones (LJ) parameters of the aromatic carbon atoms from the corresponding force field. [29][30][31][32][33][34][35] However, majority of these force fields have been developed using dataset focused on folded proteins in aqueous media. As a result, the reliability of these force fields to study the interfacial behavior of proteins has been questioned.…”