title: Observation of pH-Induced Protein Reorientation at the Water Surface.
abstract: Hydrophobins are surface-active proteins that form a hydrophobic, water-repelling film around aerial fungal structures. They have a compact, particle-like structure, in which hydrophilic and hydrophobic regions are spatially separated. This surface property renders them amphiphilic and is reminiscent of synthetic Janus particles. Here we report surface-specific chiral and nonchiral vibrational sum-frequency generation spectroscopy (VSFG) measurements of hydrophobins adsorbed to their natural place of action, the air-water interface. We observe that hydrophobin molecules undergo a reversible change in orientation (tilt) at the interface when the pH is varied. We explain this local orientation toggle from the modification of the interprotein interactions and the interaction of hydrophobin with the water solvent, following the pH-induced change of the charge state of particular amino acids.
authors.affiliation: AMOLF , Science Park 104, 1098XG Amsterdam, The Netherlands.
authors.forename: Konrad
authors.identifier: http://orcid.org/0000-0002-6853-6325
authors.initials: K
authors.lastname: Meister
authors.affiliation: Van 't Hoff Institute for Molecular Sciences, University of Amsterdam , Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Roeters
authors.affiliation: VTT Technical Research Centre of Finland Ltd. , PO. Box 1000, FI-02044 VTT Espoo, Finland.
authors.forename: Arja
authors.initials: A
authors.lastname: Paananen
authors.affiliation: Van 't Hoff Institute for Molecular Sciences, University of Amsterdam , Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors.forename: Sander
authors.initials: S
authors.lastname: Woutersen
authors.affiliation: AMOLF , Science Park 104, 1098XG Amsterdam, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Versluis
authors.affiliation: VTT Technical Research Centre of Finland Ltd. , PO. Box 1000, FI-02044 VTT Espoo, Finland.
authors.forename: Géza R
authors.initials: GR
authors.lastname: Szilvay
authors.affiliation: AMOLF , Science Park 104, 1098XG Amsterdam, The Netherlands.
authors.forename: Huib J
authors.initials: HJ
authors.lastname: Bakker
mesh_terms: D000327:Adsorption; D000388:Air; D005656:Fungal Proteins / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D014867:Water
chemical_list: D005656:Fungal Proteins; D014867:Water