Resonance Raman scattering by the green fluorescent protein and an analogue of its chromophore

Citation
P. Schellenberg et al., Resonance Raman scattering by the green fluorescent protein and an analogue of its chromophore, J PHYS CH B, 105(22), 2001, pp. 5316-5322
Citations number
51
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF PHYSICAL CHEMISTRY B
ISSN journal
1520-6106 → ACNP
Volume
105
Issue
22
Year of publication
2001
Pages
5316 - 5322
Database
ISI
SICI code
1520-6106(20010607)105:22<5316:RRSBTG>2.0.ZU;2-7
Abstract
To examine the protonation state and excitation dynamics of green fluoresce nt protein (GFP), the electronic, resonance Raman, and Fourier transform in frared spectra of GFP were compared to the corresponding spectra of an anal ogue of the GFP chromophore (4-hydroxybenzylidene-2,3-dimethyl-imidazolinon e, HEDI). Spectra were measured with GFP in both H2O and D2O and with HBDI in ordinary or deuterated ethanol under neutral, acidic, or basic condition s. The vibrational transitions were assigned with the aid of ab initio calc ulations using density functional theory methods. The results indicate that the main absorption band of GFP at 400 nm represents the neutral chromopho re and the minor band at 475 nm represents the anion. The resonance Raman s pectra of both GFP and neutral HBDI are dominated by a band in the region o f 1565 cm(-1). We assign this band to the "C=N stretch" mode, which involve s stretching of the imidazolinone C=N bond and the central C=C bond of the chromophore. The absence of resonance Raman intensity along any coordinates having substantial phenolic OH stretching character indicates that stretch ing of the O-H bond is not coupled strongly to the optical transition. Howe ver, substantial differences are observed between the resonance Raman spect ra of GFP and HBDI, suggesting that the protein does influence the structur al evolution of the excited state.