Modification of the far UV CD spectrum of LigBCen2NR upon NTD binding. Shown are far UV spectra of the apo forms and mixtures of 10 μm NTD and 10 μm either LigBCen2NR (A) or LigBCen2R (B). The ellipticities shown in A are those of uncomplexed LigBCen2NR (short dashed line), complexed NTD and LigBCen2NR after subtraction of the NTD CD spectrum (long and short dashed line), and the CD spectrum of 10 μm NTD (solid line). The ellipticities in B are those of LigBCen2R (short dashed line), a mixture of NTD and LigBCen2R after subtraction of the NTD CD spectrum (long and short dashed line), and the CD spectrum of 10 μm NTD (solid line). C, the far UV spectra of mixtures of NTD and LigBCen2NR (dashed line) or LigBCen2R (solid line) after subtraction of the CD spectra of both apo-NTD and apo-LigBCen2NR or LigBCen2R.