PMID- 18597428
OWN - NLM
STAT- MEDLINE
DCOM- 20080815
LR  - 20131121
IS  - 1520-5126 (Electronic)
IS  - 0002-7863 (Linking)
VI  - 130
IP  - 27
DP  - 2008 Jul 9
TI  - Bond selection in the photoisomerization reaction of anionic green fluorescent 
      protein and kindling fluorescent protein chromophore models.
PG  - 8677-89
LID - 10.1021/ja078193e [doi]
AB  - The chromophores of the most widely known fluorescent proteins (FPs) are 
      derivatives of a core p-hydroxybenzylidene-imidazolinon-5-one (HBI) motif, which 
      usually occurs as a phenolate anion. Double bond photoisomerization of the 
      exocyclic bridge of HBI is widely held to be an important internal conversion 
      mechanism for FP chromophores. Herein we describe the ground and excited-state 
      electronic structures and potential energy surfaces of two model chromophores: 4- 
      p-hydroxybenzylidiene-1,2-dimethyl-imidazolin-5-one anion (HBDI), representing 
      green FPs (GFPs), and 2-acetyl-4-hydroxybenylidene-1-methyl-imidazolin-5-one 
      anion (AHBMI), representing kindling FPs (KFPs). These chromophores differ by a 
      single substitution, but we observe qualitative differences in the potential 
      energy surfaces which indicate inversion of bond selection in the 
      photoisomerization reaction. Bond selection is also modulated by whether the 
      reaction proceeds from a Z or an E conformation. These configurations correspond 
      to fluorescent and nonfluorescent states of structurally characterized FPs, 
      including some which can be reversibly switched by specific illumination regimes. 
      We explain the difference in bond selectivity via substituent stabilization 
      effects on a common set of charge-localized chemical structures. Different 
      combinations of these structures give rise to both optically active (planar) and 
      twisted intramolecular charge-transfer (TICT) states of the molecules. We offer a 
      prediction of the gas-phase absorption of AHBMI, which has not yet been measured. 
      We offer a hypothesis to explain the unusual fluorescence of AHBMI in DMF 
      solution, as well as an experimental proposal to test our hypothesis.
FAU - Olsen, Seth
AU  - Olsen S
AD  - Centre for Computational Molecular Science, Australian Institute for 
      Bioengineering and Nanotechnology, The University of Queensland, St. Lucia, QLD 
      4072 Australia. s.olsen1@uq.edu.au
FAU - Smith, Sean C
AU  - Smith SC
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Am Chem Soc
JT  - Journal of the American Chemical Society
JID - 7503056
RN  - 0 (4-hydroxybenzylidene-1,2-dimethylimidazolinone)
RN  - 0 (Imidazolines)
RN  - 0 (Solutions)
RN  - 147336-22-9 (Green Fluorescent Proteins)
RN  - 8696NH0Y2X (Dimethylformamide)
SB  - IM
MH  - Dimethylformamide/chemistry
MH  - *Fluorescence
MH  - Green Fluorescent Proteins/*chemistry
MH  - Imidazolines/*chemistry
MH  - *Models, Chemical
MH  - Photochemistry
MH  - Solutions
EDAT- 2008/07/04 09:00
MHDA- 2008/08/16 09:00
CRDT- 2008/07/04 09:00
PHST- 2008/07/04 09:00 [pubmed]
PHST- 2008/08/16 09:00 [medline]
PHST- 2008/07/04 09:00 [entrez]
AID - 10.1021/ja078193e [doi]
PST - ppublish
SO  - J Am Chem Soc. 2008 Jul 9;130(27):8677-89. doi: 10.1021/ja078193e.