[en] Two-color sum-frequency generation spectroscopy (2C-SFG) is used to probe the molecular and electronic properties of an adsorbed layer of the green fluorescent protein mutant 2 (GFPmut2) on a platinum (111) substrate. First, the spectroscopic measurements, performed under different polarization combinations, and atomic force microscopy (AFM) show that the GFPmut2 proteins form a fairly ordered monolayer on the platinum surface. Next, the nonlinear spectroscopic data provide evidence of particular coupling phenomena between the GFPmut2 vibrational and electronic properties. This is revealed by the occurrence of two doubly resonant sum-frequency generation processes for molecules having both their Raman and infrared transition moments in a direction perpendicular to the sample plane. Finally, our 2C-SFG analysis reveals two electronic transitions corresponding to the absorption and fluorescence energy levels which are related to two different GFPmut2 conformations: the B (anionic) and I forms, respectively. Their observation and wavelength positions attest the keeping of the GFPmut2 electronic properties upon adsorption on the metallic surface.
Disciplines :
Physics
Author, co-author :
Dreesen, Laurent ; Université de Liège - ULiège > Département de physique > Biophotonique
Humbert, C.
Sartenaer, Y.
Caudano, Y.
Volcke, C.
Mani, A. A.
Peremans, A.
Thiry, P. A.
Hanique, S.
Frère, Jean-Marie ; Université de Liège - ULiège > Centre d'ingénierie des protéines
Language :
English
Title :
Electronic and Molecular Properties of an Adsorbed Protein Monolayer Probed by Two-Color Sum-Frequency Generation Spectroscopy
Publication date :
2004
Journal title :
Langmuir
ISSN :
0743-7463
eISSN :
1520-5827
Publisher :
American Chemical Society, Washington, United States - District of Columbia
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