Figure 6. Fe/S EPR spectra of human and bovine milk XOR.

(a) The bovine XOR sample of Figure 5(c) and (c) the human enzyme of Figure 5(d). The stick diagrams indicate the g₁, g₂ and g₃ positions for Fe/S I, II and III (data from Table 1) of the human enzyme. EPR was run at 15 K, with 5 mW microwave power at 9.355 GHz using 1.0 mT field modulation at 100 kHz; the conversion time was 40.96 ms with a time constant of 82 ms. Each spectrum is the sum of two scans. (b, d) Simulations of the bovine and human enzymes respectively using the g-values, line widths and occupancies from Table 1.