Comparison of far-UV circular dichroism and electronic absorption spectra of the wild-type BFR dimer and its variants. A, CD spectra of BFR subunit dimer (solid line), subunit dimer E47Q (· · ·), subunit dimer D50N (- · - ·), subunit dimer D126N (- · ·), and subunit dimer E47Q/D50N/D126N (- - -) in 20 mm MES buffer (pH 6.5). B, electronic spectra of BFR subunit dimer (solid line), subunit dimer E47Q (· · ·), subunit dimer D50N (- · - ·), subunit dimer D126N (- · ·), and subunit dimer E47Q/D50N/D126N (- - -) in 100 mm MES buffer (pH 6.5).