FIG. 1.

Effect of Dy³⁺ on the ¹⁵N-HSQC spectrum of the ¹³C/¹⁵N-labeled θ subunit complexed with ɛ186. Spectra were recorded in 90% H₂O-10% D₂O and 100 mM NaCl-20 mM Tris buffer (pH 7.0) at 25°C. Spectra recorded with Dy³⁺ (blue peaks) and in the absence of paramagnetic ion (red peaks) are superimposed. Lines connect pairs of diamagnetic and paramagnetic cross-peaks. Red lines indicate a negative pseudocontact shift, and blue lines indicate a positive pseudocontact shift. Cross-peaks are labeled with the residue assignment. For clarity, not all peaks are connected or labeled.