Table 1 Comparison of superoxide and peroxide-soaked Tyr34Phe MnSOD bond distances found through EXAFS fitting, neutron crystallography, and DFT calculations

From: The role of Tyr34 in proton coupled electron transfer and product inhibition of manganese superoxide dismutase

Exp.

EXAFS (Å)

Y34F MnSOD + Superoxide

EXAFS (Å)

Y34F MnSOD + Peroxide

Neutron Structure (Å)

Y34F MnSOD + Peroxide

Mn-Nε2(H26)

2.15

2.15

2.17

Mn-Nε2(H74)

2.15

2.15

2.23

Mn-Nε2(H163)

2.15

2.15

2.21

Mn-Oδ2(D159)

2.11

2.11

2.13

Mn-O1(LIG)

2.11

2.11

2.00

Mn-O2(LIG)a

2.44

2.44

2.34

Calc.

DFT (Å)

Y34F Mn2+SOD + −O2H

DFT (Å)

Y34F Mn3+SOD + −O2H

DFT (Å)b

Y34F Mn2+SOD + ●O2H

S

5/2

2

3

Mn-Nε2(H26)

2.28 (0.11)

2.00 (0.17)

2.12 (0.05)

Mn-Nε2(H74)

2.20 (0.03)

2.07 (0.16)

2.16 (0.07)

Mn-Nε2(H163)

2.16 (0.03)

2.19 (0.06)

2.17 (0.04)

Mn-Oδ2(D159)

2.17 (0.04)

2.01 (0.12)

2.01 (0.12)

Mn-O1(LIG)

2.10 (0.10)

1.82 (0.18)

2.37 (0.37)

Mn-O2(LIG)a

2.38 (0.04)

2.60 (0.26)

3.03 (0.69)

  1. aThe second oxygen of the dioxygen ligand is not directly bound to the Mn ion.
  2. bBroken-symmetry geometry optimization of Mn2+-●O2H with S = 2 collapses to a Mn3+-−O2H complex.
  3. cThe absolute value of the difference between the neutron structure bond length and the DFT bond length are given in parenthesis.
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