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. Author manuscript; available in PMC: 2008 Dec 18.
Published in final edited form as: Biochemistry. 2007 Nov 21;46(50):14403–14417. doi: 10.1021/bi701575n

Figure 1.

Figure 1

(A) Normalized absorption and fluorescence (λex = 400 nm) spectra of YFP 10C at pH 6.0. Arrows pointing upwards and downwards indicate the excitation and emission wavelengths relevant to anisotropy measurements. Protonation states of the chromophore are annotated for both absorption bands. (B) Time-resolved fluorescence anisotropy measured for wild-type GFP at pH 7.8 (λem = 508 nm) and YFP 10C at pH 6.0 (λem = 527 nm) with 400 nm one-photon excitation. (C) Dependence of one-photon excited fluorescence anisotropy on β, the angle between absorption (blue arrow) and emission (orange arrow) dipole moments. Three different cases are illustrated, with β = 0, 54.7 (magic angle), and 90°, respectively. (D) Excited-state proton transfer in GFP is illustrated, with the neutral and anionic states of the chromophore shown in blue and green, respectively.