Interaction of W59, the 40-to-57 Ω-loop (yellow) and the 71-to-85 Ω-loop (orange) in human Fe(II) G41S cyt c (PDB: 3NWV). The amino acid residues analyzed in NMR spectra, and the heme, are shown in green, residues 41, 67, and 80 in salmon, oxygen in red and nitrogen in blue. View is rotated ~100° around a horizontal axis, relative to figure 1.