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Title: Probing microhydration effect on the electronic structure of the GFP chromophore anion: Photoelectron spectroscopy and theoretical investigations

The photophysics of the Green Fluorescent Protein (GFP) chromophore is critically dependent on its local structure and on its environment. Despite extensive experimental and computational studies, there remain many open questions regarding the key fundamental variables that govern this process. One outstanding problem is the role of autoionization as a possible relaxation pathway of the excited state under different environmental conditions. This issue is considered in our work through combined experimental and theoretical studies of microsolvated clusters of the deprotonated p-hydroxybenzylidene-2,3-dimethylimidazolinone anion (HBDI{sup −}), an analog of the GFP chromophore. Through selective generation of microsolvated structures of predetermined size and subsequent analysis of experimental photoelectron spectra by high level ab initio methods, we are able to precisely identify the structure of the system, establish the accuracy of theoretical data, and provide reliable description of auto-ionization process as a function of hydrogen-bonding environment. Our study clearly illustrates the first few water molecules progressively stabilize the excited state of the chromophore anion against the autodetached neutral state, which should be an important trait for crystallographic water molecules in GFPs that has not been fully explored to date.
Authors:
;  [1] ;  [2] ; ;  [3] ; ;  [4]
  1. Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)
  2. (United States)
  3. William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, K8-91, P.O. Box 999, Richland, Washington 99352 (United States)
  4. Physical Sciences Division, Pacific Northwest National Laboratory, K8-88, P.O. Box 999, Richland, Washington 99352 (United States)
Publication Date:
OSTI Identifier:
22493311
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 143; Journal Issue: 22; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ACCURACY; ANIONS; AUTOIONIZATION; CRYSTAL STRUCTURE; ELECTRONIC STRUCTURE; EXCITED STATES; FLUORESCENCE; IMIDAZOLES; MOLECULES; PHOTOELECTRON SPECTROSCOPY; PROBES; PROTEINS; RELAXATION