title: How water layers on graphene affect folding and adsorption of TrpZip2.
abstract: We present a computational study of the folding of the Trp-rich β-hairpin TrpZip2 near graphene, a surface of interest as a platform for biosensors. The protein adsorbs to the surface, populating a new bound, folded state, coexisting with extended, adsorbed conformations. Adsorption and folding are modulated by direct interactions between the indole rings of TrpZip2 and the rings on the graphene surface, as well as by indirect water-mediated interactions. In particular, we observe strong layering of water near graphene, ice-like water configurations, and the formation of short lived hydrogen-bonds between water and protein. In order to study the effect of this layering in more detail, we modified the interactions between graphene and water to obtain two extreme cases: (1) enhanced layering of water that prevents the peptide from penetrating the water layer thereby enabling it to fold to a bulk-like structure, and (2) disruption of the water layer leading to adsorption and unfolding of the protein on the surface. These studies illuminate the roles of direct and solvent mediated interactions in modulating adsorption and folding of proteins on surfaces.
authors.affiliation: Insitute of Computational Science, Faculty of Informatics, University of Lugano, Switzerland.
authors.forename: Emanuel K
authors.initials: EK
authors.lastname: Peter
authors.affiliation: Insitute of Computational Science, Faculty of Informatics, University of Lugano, Switzerland.
authors.forename: Mrigya
authors.initials: M
authors.lastname: Agarwal
authors.affiliation: Department of Chemistry and Biochemistry and Department of Physics, University of California Santa Barbara, California 93106, USA.
authors.forename: BongKeun
authors.initials: B
authors.lastname: Kim
authors.affiliation: Insitute of Computational Science, Faculty of Informatics, University of Lugano, Switzerland.
authors.forename: Igor V
authors.initials: IV
authors.lastname: Pivkin
authors.affiliation: Department of Chemistry and Biochemistry and Department of Physics, University of California Santa Barbara, California 93106, USA.
authors.forename: Joan-Emma
authors.initials: JE
authors.lastname: Shea
mesh_terms: D000327:Adsorption; D000595:Amino Acid Sequence; D006108:Graphite / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry* / Q000302:isolation & purification; D014867:Water / Q000737:chemistry*
chemical_list: D011506:Proteins; C539234:Trpzip2 protein; D014867:Water; D006108:Graphite