Figure 1. Complex of nitrite reductase and pseudoazurin. Nitrite reductase is shown in spacefill, with the subunits in blue, pink, and green. The 20 best pseudoazurin orientations are shown as C α traces. The coppers are shown as green spheres and the positions of the gadolinium ions in the CLaNP molecules as orange spheres. (Reprinted with permission from [ 26]. © 2008 Elsevier.)
|
Figure 2. Experimental evidence and computer simulations of the encounter complex of cytochrome c and cytochrome c peroxidase. (a) Observed (solid circles) and calculated (open symbols) PREs for cytochrome c residues in complex with spin‐labeled cytochrome c peroxidase T288C. The experimental PREs are in black, the PREs back‐calculated from the specific complex are in blue, the PREs of the simulated encounter complex are in green, and the combination of the latter two at a 30% population fraction of the ensemble are in red. (b) Simulated cytochrome c–cytochrome c peroxidase encounter complex. Cytochrome c peroxidase is shown as a cartoon with the heme in cyan. The centers of mass of cytochrome c are shown as spheres, colored to indicate the density of the distributions, decreasing from red to blue. Densities were determined by counting the number of neighbors within 2 Å. The highest densities denote the most favorable electrostatic orientations. (Reprinted with permission from [ 44]. © 2010 American Chemical Society.)
|
Figure 3. Ensemble of the cytochrome c/adrenodoxin complexes from RDC simulation illustrates the intermolecular dynamics. (a) Adrenodoxin is shown as a blue ribbon with its Fe 2S 2 cluster as orange spheres. The geometrical centers of cytochrome c are represented by red spheres. The frame of the magnetic susceptibility tensor experienced for each conformation of cytochrome c is represented as green sticks. (b) Plots of RDCs observed for adrenodoxin in the complex and the RDCs simulated for the adrenodoxin in the dynamic ensemble. Black and red circles represent observed and calculated RDC, respectively. Green triangles represent calculated RDC for adrenodoxin in a hypothetical single‐orientation complex. The dashed lines indicate the significance level, 2.5 Hz for the 100% bound adrenodoxin. In the native complex the RDCs of adrenodoxin are insignificant, caused by extensive motion averaging relative to the aligned cytochrome c. (Reprinted from [ 17], with kind permission from Springer Science and Business Media.)
|
Figure 4. Example of an NMR titration experiment and binding map. (a) CSPs (Δδ Bind = Δδ obs) in the HSQC spectrum of  ‐labeled Nostoc plastocyanin upon titration with cytochrome f. The fitted K A = 26(±1) × 10 3 M −1. (b) The Δδ avg, max for each amide was used to color the residues of plastocyanin, from blue via yellow and orange to red for increasing perturbations. Gray, no data. (Reprinted with permission from [ 64]. © 2005 American Chemical Society.)
|
Figure 5. Maximum average CSPs. (a) Shifts of cytochrome c upon complex formation with cytochrome c peroxidase. (b) Shifts of cytochrome b 5 upon complex formation with myoglobin. (Reprinted with permission from [ 54, 65]. © 2001 and 2003 American Chemical Society.)
|
Figure 6. Labeling scheme of the redox partners adrenodoxin and adrenodoxin reductase (a) and example  – TROSY spectrum (b). Adrenodoxin reductase C364S/C145S/Q232C/K236C was tagged with Lu‐CLaNP‐5 (black contours) and Tm‐CLaNP‐5 (red contours) and added to  / ‐adrenodoxin. TROSY spectra were acquired of 30 µM adrenodoxin reductase and 25 µM of adrenodoxin at 285 K on a Bruker Avance DMX 600 spectrometer equipped with a TCI‐Z‐GRAD cryoprobe, in 20 mM sodium phosphate, pH 7.4, 6% D 2O (v/v), and 100 mM NaCl. Adrenodoxin is displayed as a ribbon with the HN atoms and Fe 2S 2 cluster as CPK colored spheres, adrenodoxin reductase as a cartoon, with the FAD and lanthanide tag in sticks with the lanthanide ion as a red sphere. The intermolecular PCSs are obtained by subtraction of the chemical shifts of the black resonances from those of the corresponding red ones.
|