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          Institute: MPI für biophysikalische Chemie     Collection: Molekulare Biologie (Dr. Thomas M. Jovin)     Display Documents

ID: 17157.0, MPI für biophysikalische Chemie / Molekulare Biologie (Dr. Thomas M. Jovin)
Resonance energy transfer in a calcium concentration-dependent cameleon protein
Authors:Habuchi, S.; Cotlet, M.; Hofkens, J.; Dirix, G.; Michiels, J.; Vanderleyden, J.; Subramaniam, V.; De Schryver, F. C.
Date of Publication (YYYY-MM-DD):2002-12
Title of Journal:Biophysical Journal
Issue / Number:6
Start Page:3499
End Page:3506
Review Status:Peer-review
Audience:Not Specified
Abstract / Description:We report investigations of resonance energy transfer in the green fluorescent protein and calmodulin-based fluorescent indicator constructs for Ca2+ called cameleons using steady- state and time-resolved spectroscopy of the full construct and of the component green fluorescent protein mutants, namely ECFP (donor) and EYFP (acceptor). EYFP displays a complicated photophysical behavior including protonated and deprotonated species involved in an excited-state proton transfer. When EYFP is excited in the absorption band of the protonated species, a fast nonradiative deactivation occurs involving almost 97% of the excited protonated population and leading to a low efficiency of excited-state proton transfer to the deprotonated species. ECFP displays a multiexponential fluorescence decay with a major contributing component of 3.2 ns. The time- resolved fluorescence data obtained upon excitation at 420 nm of Ca2+-free and Ca2+-bound YC3.1 cameleon constructs point to the existence of different conformations of calmodulin dependent on Ca2+ binding. Whereas steady-state data show only an increase in the efficiency of energy transfer upon Ca2+ binding, the time-resolved data demonstrate the existence of three distinct conformations/populations within the investigated sample. Although the mechanism of the interconversion between the different conformations and the extent of interconversion are still unclear, the time-resolved fluorescence data offer an estimation of the rate constants, of the efficiency of the energy transfer, and of the donor- acceptor distances in the Ca2+-free and Ca2+-bound YC3.1 samples.
Comment of the Author/Creator:Date: 2002, DEC
Last Change of the Resource (YYYY-MM-DD):2004-07-30
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für biophysikalische Chemie/Abt. Thomas Jovin / 060
External Affiliations:Katholieke Univ Leuven, Dept Chem, Celestijnenlaan 200F, B-3001; Heverlee, Belgium; Katholieke Univ Leuven, Dept Chem, B-3001 Heverlee, Belgium; Ctr Microbial & Plant Genet, B-3001 Heverlee, Belgium
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