Ultrafast Fluorescence Depolarisation in the Yellow Fluorescent Protein due to Its Dimerisation

Authors

  • Gregor Jung Dr.,

    1. Department of Chemistry, University of California, Berkeley and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720-1460, USA
    2. Current address: Biophysical Chemistry, Saarland University, Building 9.2, 66123 Saarbruecken, Germany, Fax: (+49) 0681-302-64846
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  • Yingzhong Ma Dr.,

    1. Department of Chemistry, University of California, Berkeley and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720-1460, USA
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  • Bradley S. Prall,

    1. Department of Chemistry, University of California, Berkeley and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720-1460, USA
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  • Graham R. Fleming Prof.

    1. Department of Chemistry, University of California, Berkeley and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720-1460, USA
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Abstract

Transient absorption spectroscopy with sub-100 fs time resolution was performed to investigate the oligomerisation behaviour of eYFP in solution. A single time constant τAD=2.2±0.15 ps is sufficient to describe the time-resolved anisotropy decay up to at least 200 ps. The close contact of two protein barrels is deduced as the exclusive aggregation state in solution. From the final anisotropy r=0.28±0.02, the underlying quaternary structure can be traced back to the somewhat distorted structure of the dimers of wt-GFP. The use of autofluorescent proteins as rulers in Förster resonance energy transfer (FRET) measurements may demand polarisation-sensitive detection of the fluorescence with high time resolution.

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