Table 1.

EXAFS fitting results for ΔnifH MoFe protein samples matured for varying lengths of time

Incubation time, min	Fe-S			Fe-Fe (short)			Fe- Fe (long)			ΔE0, eV	Error
	N	R, Å	σ2, Å2	N	R, Å	σ2, Å2	N	R, Å	σ2, Å2
0	3.50	2.30	0.0060	0.50	2.49	0.0040	2.50	2.70	0.0119	−12.7	0.352
5	3.50	2.31	0.0054	1.00	2.52	0.0065	2.25	2.73	0.0099	−12.0	0.303
20	3.50	2.31	0.0054	1.00	2.52	0.0063	2.25	2.72	0.0104	−12.6	0.323
60	3.50	2.32	0.0048	1.50	2.55	0.0116	1.75	2.77	0.0100	−10.8	0.332
120	3.50	2.32	0.0051	1.50	2.55	0.0094	1.75	2.76	0.0097	−10.8	0.336

The data were fit over the k range 2 to 15.7 Å⁻¹. The variables are coordination number, N; interatomic distance, R (Å); mean-square thermal and static deviation in R, σ² (Ų); and the shift in the threshold energy, ΔE₀ (eV). R, σ², and ΔE₀ were allowed to float during the fitting process in which N was systematically varied; a single ΔE₀ was used for each fit. The estimated uncertainties in R and σ² are ± 0.02 and ± 0.0001 Ų, respectively (30). There is a 10–20% uncertainty in N (31). Error is reported as F/no. of points, where F = [Σk⁶(χ_exptl − χ_calcd)²/ Σk⁶χ_exptl²] (27).