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Analysis of photoinduced electron transfer in AppA

Paper ID Volume ID Publish Year Pages File Format Full-Text
28075 44058 2009 8 PDF Available
Title
Analysis of photoinduced electron transfer in AppA
Abstract

The fluorescence dynamics of isoalloxazine (Iso) in AppA were analyzed in order to elucidate the mechanism of photoinduced electron transfer (ET) in a photosensing flavoprotein, blue-light sensing using flavin (BLUF) of AppA. The ET parameters contained in Kakitani and Mataga ET theory (KM theory) were determined by a non-linear least squares method using atomic coordinates obtained by molecular dynamic simulation (MD). The ET rate from Tyr21 to the excited state of isoalloxazine (Iso*) was slightly slower than that from Trp104 to Iso*. It was found that frequency factor ν0 in the ET process from Tyr21 to Iso* was 16 times higher than the one from Tyr35 in a non-photosensing flavoprotein, flavin mononucleotide binding protein (FBP). Transferred charges and interaction energies in the systems of Iso*-Gln63-Trp104 and Iso*-Gln63-Tyr21 were obtained by a semi-empirical molecular orbital method (MO). Forty configurations of these systems by MD structures at 50 ps time intervals were geometrically optimized with the PM3 method. The mean charges at Iso* over 40 configurations were −0.254 ± 0.057 in the Iso*-Gln63-Trp104 system and 0.016 ± 0.002 in the Iso*-Gln63-Tyr21 system. Mean interaction energies among Iso*, Gln63 and Trp104 or Tyr21 were −11.7 ± 1.02 kcal/mol in the Iso*-Gln63-Trp104 system. The extraordinarily high ν0 value in ET from Tyr21 to Iso* was elucidated by the H bond chain from Tyr21 to Iso* through Gln63, though MO results by PM3 could not elucidate it.

Keywords
Photoreceptor; Photoinduced charge transfer; Molecular dynamic simulation; Semi-empirical molecular orbital method; BLUF; AppA; Analysis of fluorescence dynamics
First Page Preview
Analysis of photoinduced electron transfer in AppA
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 207, Issues 2–3, 25 September 2009, Pages 274–281
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering