Fig. 6.

X-ray Guinier analyses of the full-length FH and SCR-6/8 allotypes titrated with zinc. In all panels, the open symbols correspond to the experimental data and the filled symbols correspond to those used for the R_G and R_XS straight line fits. Data correspond to one FH Tyr402 allotype (018DK) in (a), (c), and (e) and one FH His402 allotype (030TJ) in (b), (d), and (f), both at 0.9 mg/ml, and SCR-6/8 Tyr402 (g and i) and SCR-6/8 His402 (h and j), both at 0.2 mg/ml. Data for the Tyr402 allotype of FH and SCR-6/8 are shown in blue from 0.2 μM to 120 μM ZnSO₄ and in cyan from 200 μM to 600 μM ZnSO₄. Data for the His402 allotype of FH and SCR-6/8 are shown in red from 0.2 μM to 120 μM ZnSO₄ and in pink from 200 μM to 600 μM ZnSO₄. (a and b) Guinier R_G plots of ln I(Q) versus Q² for FH Tyr402 and FH His402 allotypes titrated with ZnSO₄ concentrations of 0.2 μM (O), 2 μM (□), 6 μM (Δ), 20 μM (▿), 60 μM (◊), 120 μM (⎔), 200 μM (O), and 600 μM (Δ). The Q fit ranges were 0.08–0.13 nm^− 1 for 0.2 μM to 120 μM ZnSO₄ and 0.03–0.16 nm^− 1 for 200 μM to 600 μM ZnSO₄. The zinc concentrations are numerically labelled as shown. (c and d) The corresponding Guinier cross-sectional R_XS-1 fits of ln I(Q)Q versus Q² for the two FH allotypes with zinc using a Q range of 0.16–0.26 nm^− 1. (e and f) The corresponding Guinier cross-sectional R_XS-2 fits for the two FH allotypes with zinc using a Q range of 0.4–0.8 nm^− 1. (g and h) Guinier R_G plots for the SCR-6/8 Tyr402 and His402 allotypes at 0.2 mg/ml titrated with ZnSO₄ at concentrations of 0 μM (○), 2 μM (□), 6 μM (Δ), 20 μM (▿), 60 μM (◊), 120 μM (⎔), 200 μM (O), 300 μM (□), and 600 μM (Δ). The Q fit ranges were 0.16–0.5 nm^− 1 for 0.2 μM to 120 μM ZnSO₄ and 0.06–0.11 nm^− 1 for 200 μM to 600 μM ZnSO₄. (i and j) The corresponding Guinier cross-sectional R_XS fits for the SCR-6/8 allotypes using a Q range of 0.55–1.0 nm^− 1.