Figure 7.
Evidence from 15N NMR spectra that the labeled signals (□ and •) of reduced [U-15N]-IscR(WT) arise from nuclei affected by electron-nuclear (hyperfine) interactions. (A, B) The chemical shifts of the labeled peaks exhibit anti-Curie shifts as a function of temperature as expected for an Fe-S cluster ligand (delay value 5.0 ms). (C, D) Spectra taken as two different delay values (1.0 s and 5.0 ms) between the data collection pulses suggest that the labeled peaks correspond to rapidly relaxing nuclei as expected for a cluster ligand.