title: Suspended crystalline films of protein hydrophobin I (HFBI).
abstract: Protein interfaces play an essential role in both natural and man-made materials as stabilizers, sensors, catalysts, and selective channels for ions and small molecules. Probing the molecular arrangement within such interfaces is of prime importance to understand the relation between structure and functionality. Here we report on the preparation and characterization of large area suspended crystalline films of class II hydrophobin HFBI. This small, amphiphilic globular protein readily self-assembles at the air-water interface into a 2D hexagonal lattice which can be transferred onto a holey carbon electron microscopy grid yielding large areas of hundreds of square micrometers intact hydrophobin film spun across micron-sized holes. Fourier transform analysis of low-dose electron microscopy images and selected area electron diffraction profiles reveal a unit cell dimension a=5.6±0.1nm, in agreement with reported atomic force microscopy studies on solid substrates and grazing incidence X-ray scattering experiments at the air-water interface. These findings constitute the first step towards the utilization of large-area suspended crystalline hydrophobin films as membranes for ultrapurification and chiral separation or as biological substrates for ultrafast electron diffraction.
authors.affiliation: Laboratory of Macromolecular and Organic Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, The Netherlands; Institute for Complex Molecular Systems, Eindhoven University of Technology, The Netherlands. Electronic address: a.s.oude.vrielink@tue.nl.
authors.forename: Anneloes S
authors.initials: AS
authors.lastname: Oude Vrielink
authors.affiliation: Laboratory for Materials and Interface Chemistry and Soft Matter CryoTEM Research Unit, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, The Netherlands; Institute for Complex Molecular Systems, Eindhoven University of Technology, The Netherlands. Electronic address: P.H.H.Bomans@tue.nl.
authors.forename: Paul H H
authors.initials: PH
authors.lastname: Bomans
authors.affiliation: Research Group Coherence and Quantum Technology, Department of Applied Physics, Eindhoven University of Technology, The Netherlands. Electronic address: E.J.D.Vredenbregt@tue.nl.
authors.forename: Edgar J D
authors.initials: EJ
authors.lastname: Vredenbregt
authors.affiliation: Institute for Complex Molecular Systems, Eindhoven University of Technology, The Netherlands; Laboratory for Materials and Interface Chemistry and Soft Matter CryoTEM Research Unit, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, The Netherlands. Electronic address: M.J.M.Wirix@tue.nl.
authors.forename: Maarten J M
authors.initials: MJ
authors.lastname: Wirix
authors.affiliation: Laboratory for Materials and Interface Chemistry and Soft Matter CryoTEM Research Unit, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, The Netherlands; Institute for Complex Molecular Systems, Eindhoven University of Technology, The Netherlands. Electronic address: N.A.J.M.Sommerdijk@tue.nl.
authors.forename: Nico A J M
authors.initials: NA
authors.lastname: Sommerdijk
authors.affiliation: Research Group Coherence and Quantum Technology, Department of Applied Physics, Eindhoven University of Technology, The Netherlands; Institute for Complex Molecular Systems, Eindhoven University of Technology, The Netherlands. Electronic address: O.J.Luiten@tue.nl.
authors.forename: O J
authors.initials: OJ
authors.lastname: Luiten
authors.affiliation: Laboratory of Macromolecular and Organic Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, The Netherlands; Institute for Complex Molecular Systems, Eindhoven University of Technology, The Netherlands. Electronic address: I.Voets@tue.nl.
authors.forename: Ilja K
authors.initials: IK
authors.lastname: Voets
mesh_terms: D018360:Crystallography, X-Ray; D005656:Fungal Proteins / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D018625:Microscopy, Atomic Force; D014242:Trichoderma / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins
keywords: Chiral separation membranes; Hydrophobin; Self-assembly; Ultrafast electron diffraction; Ultrafiltration membranes