Donor-Acceptor Distance-Dependence of Photoinduced Electron-Transfer Rate in Flavoproteins
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- 作者：Fumio Tanaka ; Haik Chosrowjan ; Seiji Taniguchi ; Noboru Mataga ; Kyosuke Sato ; Yasuzo Nishina ; Kiyoshi Shiga
- 刊名：Journal of Physical Chemistry B
- 出版年：2007
- 出版时间：May 24, 2007
- 年：2007
- 卷：111
- 期：20
- 页码：5694 - 5699
- 全文大小：137K
- 年卷期：v.111,no.20(May 24, 2007)
- ISSN：1520-5207
文摘
Ultrafast fluorescence quenching of flavin in flavodoxin from Megasphaera elsdenii was investigated bymeans of a fluorescence up-conversion method. Fluorescence lifetimes of flavodoxin from M. elsdenii wereestimated to be 
1 ~ 165 fs (0.97%) and 2 ~ 10 ps (0.03%). Correlation of photoinduced electron-transferrates (kET) with averaged distances (Dav) between isoalloxazine and nearby tryptophan or tyrosine was examinedand obtained an empirical equation of ln kET vs Dav by means of a nonlinear least-squares method usingreported data together with flavodoxin from M. elsdenii. The values of Dav were calculated from X-ray structuresof the flavoproteins. The ln kET was approximately linear at Dav shorter than 7 Å. The model free empiricalequation was expressed as ln kET = 29.7 + (-0.327Dav + 2.84 × 10-5)/(0.698 - Dav2). We also analyzed theobserved values of ln kET with Marcus theory, but could not obtain reasonable results. Our analysis suggeststhat the average distance, rather than the shortest (edge to edge) distance or interplanar angles between thearomatics rings, is the key factor in the process of the photoinduced electron transfer in these flavoproteins.
1 ~ 165 fs (0.97%) and 2 ~ 10 ps (0.03%). Correlation of photoinduced electron-transferrates (kET) with averaged distances (Dav) between isoalloxazine and nearby tryptophan or tyrosine was examinedand obtained an empirical equation of ln kET vs Dav by means of a nonlinear least-squares method usingreported data together with flavodoxin from M. elsdenii. The values of Dav were calculated from X-ray structuresof the flavoproteins. The ln kET was approximately linear at Dav shorter than 7 Å. The model free empiricalequation was expressed as ln kET = 29.7 + (-0.327Dav + 2.84 × 10-5)/(0.698 - Dav2). We also analyzed theobserved values of ln kET with Marcus theory, but could not obtain reasonable results. Our analysis suggeststhat the average distance, rather than the shortest (edge to edge) distance or interplanar angles between thearomatics rings, is the key factor in the process of the photoinduced electron transfer in these flavoproteins.