FIGURE 6.

Absorption spectra of domain swap mutants. A–F show spectra after dark assembly (solid lines). The protein variants Agp2 (A), Agp2_Pas1 (B), and Agp2_Hiskin1 (F) have a Pfr ground state. These samples were irradiated with far-red (dash-dotted lines). The Agp2_Pas1 dark-adapted sample contains a mixture of Pr and Pfr due to slow dark conversion. Agp2_Gaf1 (C), Agp2_Phy1 (D), and Agp1 (E), which was analyzed in parallel as a control, have a Pr dark state and were irradiated with red light (dashed lines). In G–K, spectra during dark conversion are given. Each sample was first irradiated with saturating red or far-red light. Subsequently, spectra were recorded in 10-min intervals up to 40 min. The direction of absorbance changes is indicated by the arrows. In Agp2 (G), Agp_Pas1 (H), and Agp2_Hiskin1 (K), dark conversion proceeds from Pr to Pfr; in Agp2_Gaf1 (I) it proceeds from Pfr to Pr. No dark conversion was found for Agp2_Phy1 (J).