title: Structural control of surface layer proteins at electrified interfaces investigated by in situ Fourier transform infrared spectroscopy.
abstract: In situ Fourier Transform Infrared (FTIR) Spectroscopy complemented by Electrochemical Quartz Microbalance (EQMB) investigations allowed a detailed insight into the influence of the electrode potential on competing adsorption processes and bonding mechanisms of buffer ions and S-layer protein molecules of Lysinibacillus sphaericus CCM2177 at an electrified liquid/gold interface. The S-layer proteins adsorb on gold polarized positively of the point of zero charge by displacing perchlorate anions in the Helmholtz plane by their carboxylate groups. This is indicated by an increase of the peptide and carboxylate infrared absorption signals accompanied by a decrease of the perchlorate signal. S-layers interlinked laterally with Ca(2+) ions, positive of the point of zero charge, resulted in the formation of a crystalline layer participating in the Helmholtz layer. In contrast to the absence of the Ca(2+)-linkers, S-layers remain structurally intact also in the negative polarization domain where the Helmholtz layer is solely sustained by mainly solvated cations without participation of the negatively charged protein carboxylate functions.
authors.affiliation: University of Vienna, Department of Physical Chemistry, Währinger Strasse 42, A-1090 Vienna, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Zafiu
authors.forename: Günter
authors.initials: G
authors.lastname: Trettenhahn
authors.forename: Dietmar
authors.initials: D
authors.lastname: Pum
authors.forename: Uwe Bernd
authors.initials: UB
authors.lastname: Sleytr
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kautek
mesh_terms: D000327:Adsorption; D002118:Calcium / Q000737:chemistry; D008562:Membrane Glycoproteins / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties
chemical_list: D008562:Membrane Glycoproteins; D011506:Proteins; C055764:S-layer proteins; D002118:Calcium