Figure 2.

Enhancement of fluorescence intensities of ANA variants following oxygen binding. (A) Fluorescence intensity changes of protoANA2 with amino acid substitutions at the 230th residue (GX-variants) were measured following oxygen binding. (B) Fluorescence intensity changes of protoANA3 with an amino acid substitution at the 229th residue (XF-variants) were measured following oxygen binding. In (A) and (B), emission spectra of ANA variants (1.5–2 μM) were recorded in the absence or presence of oxygen, and fluorescence intensity changes (fold) were determined at 527 nm. Fluorescence intensities of ANA variants were expressed relative to that in the absence of oxygen (1.0-fold). Data are presented as means ± s.d. from three replicates.