Transitions
contributing to EPR absorption line shapes of manganese
lipoxygenase at two frequencies: (A) calculations at 9.4 GHZ (X) of
intensities for different angular orientations and pairs of energy
levels (dots) and (B) line shapes resulting from these transitions;
(C) an experimental 94 GHz (W) EPR spectrum of manganese lipoxygenase
and (D) the same calculation of line shapes shown in (B) but at the
higher EPR frequency 94 GHz. Colors show the pair of energy levels
involved in significant transitions (level “1” is lowest
in energy): 1 → 2 (red), 1 → 3 (gray), 1 → 4
(orange), 2 → 3 (black), 2 → 4 (green), 3 → 4
(light brown), 3 → 5 (light blue), 4 → 5 (purple) and
5 → 6 (dark green). Calculation parameters included zero field
energies D = 0.1 cm–1 and E/D = 0.06. The inset in (C) compares the
calculated (lower) and experimental (upper) hyperfine details in the
central transition of manganese lipoxygenase. The straight red lines
in (C) indicate the same magnetic field range in the inset and the
full spectrum. (A) and (B) are adapted with permission from Figure
9 of ref (31) 2009,
Springer; and (C) and (D) are adapted with permission from ref (27) 2001, Springer.