PMID- 17696529
OWN - NLM
STAT- MEDLINE
DCOM- 20071002
LR  - 20131121
IS  - 1520-6106 (Print)
IS  - 1520-5207 (Linking)
VI  - 111
IP  - 35
DP  - 2007 Sep 6
TI  - Ab initio prediction of tryptophan fluorescence quenching by protein electric 
      field enabled electron transfer.
PG  - 10335-9
AB  - We report quantum mechanical-molecular mechanical (QM-MM) predictions of 
      fluorescence quantum yields for 20 tryptophans in 17 proteins, whose yields span 
      the range from 0.01 to 0.3, using ab initio computed coupling matrix elements for 
      photoinduced electron transfer from the 1La excited indole ring to a local 
      backbone amide. The average coupling elements span the range 140-1000 cm-1, 
      depending on tryptophan rotamer conformation. The matrix elements were from the 
      singles configuration interaction matrix, and were largely insensitive to which 
      of the three basis sets was used. Large fluctuations were seen on the time scale 
      of tens of femtoseconds, caused primarily by side chain and backbone torsional 
      variations for 150 ps of dynamics at 300 K. The largest coupling occurs for the 
      chi1 = -60 degrees rotamer and is purely through-bond. There is no apparent 
      correlation between the coupling magnitude and quantum yield, which is still 
      dominated by energy gap and reorganization energy. The source of error bars for 
      predicted quenching rates using the weak coupling golden rule may be due to 
      inaccurate averaged Franck-Condon weighted densities because of inadequate 
      simulation times and parameters and/or to failure of the weak coupled golden rule 
      used in these predictions because of the broad distribution of Landau-Zener 
      probabilities arising from the large variable coupling.
FAU - Callis, Patrik R
AU  - Callis PR
AD  - Department of Chemistry and Biochemistry, Montana State University, Bozeman, 
      Montana 59717, USA. pcallis@montana.edu
FAU - Petrenko, Alexander
AU  - Petrenko A
FAU - Muino, Pedro L
AU  - Muino PL
FAU - Tusell, Jose R
AU  - Tusell JR
LA  - eng
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
DEP - 20070816
PL  - United States
TA  - J Phys Chem B
JT  - The journal of physical chemistry. B
JID - 101157530
RN  - 0 (Proteins)
RN  - 8DUH1N11BX (Tryptophan)
SB  - IM
MH  - Computer Simulation
MH  - Electrochemistry
MH  - Fluorescence
MH  - Kinetics
MH  - Models, Molecular
MH  - Proteins/*chemistry
MH  - Quantum Theory
MH  - Tryptophan/*chemistry
EDAT- 2007/08/19 09:00
MHDA- 2007/10/03 09:00
CRDT- 2007/08/19 09:00
PHST- 2007/08/19 09:00 [pubmed]
PHST- 2007/10/03 09:00 [medline]
PHST- 2007/08/19 09:00 [entrez]
AID - 10.1021/jp0744883 [doi]
PST - ppublish
SO  - J Phys Chem B. 2007 Sep 6;111(35):10335-9. doi: 10.1021/jp0744883. Epub 2007 Aug 
      16.