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Excitation energy transfer in GFP-X-CFP model peptides (X = amino acids): Direct Versus through-bridge energy transfers

Authors

  • Tsutomu Kawatsu,

    1. Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano-nishihiraki-cho, Sakyo-ku, Kyoto 606-8103, Japan
    2. Institute for Molecular Science, National Institute of Natural Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
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  • Jun-ya Hasegawa

    Corresponding author
    1. Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano-nishihiraki-cho, Sakyo-ku, Kyoto 606-8103, Japan
    2. Quantum Chemical Research Institute (QCRI), Kyodai Katsura Venture Plaza, North building 106, 1-36 Goryo-Oohara, Nishikyo-ku, Kyoto 615-8245, Japan
    3. Department of Synthetic Chemistry and Biological Chemistry, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
    • Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano-nishihiraki-cho, Sakyo-ku, Kyoto 606-8103, Japan
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Abstract

The excitation energy transfer (EET) between a fluorescent resonance energy transfer (FRET) pair, cyan fluorescent protein chromophore (CFPc)/ green fluorescent protein chromophore (GFPc), is used for measuring molecular proximity in experimental studies. In this article, the role of the bridging protein media has been investigated using the quantum chemical calculations for the EET electronic coupling. We adopted a model peptide connecting GFPc and CFPc, a GFPc-X-CFPc model, and examined the X (amino acids) dependence. The major part of the EET coupling element arises from the direct interaction between GFPc and CFPc via the Förster mechanism. The magnitude of the through-X interactions vary for the type of residues. The contribution of the X was, however, at most 10% of the total value. Together with the contributions from through-peptide and charge-transfer types, X gives minor modifications to the total coupling via the super-exchange mechanism. © 2012 Wiley Periodicals, Inc.

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