Table III.

Results of the refinement (explanation with a theoretical model) of the EXAFS spectra of model compounds using the DL-Excurve program

The graphs of the fits for Cu(I/II)-glutathione, Cu(II)-His, and Cu(II)-NA at pH 7 are shown in Figure 3. The refinements of model compounds that were more relevant for C. helmsii [aqueous Cu(II), Cu(II)-citrate, and Cu(II)-malate] are shown in the companion article (Küpper et al., 2009) about Cu metabolism in that species. EF, Fermi energy, defines the threshold for the EXAFS spectra (Rehr and Albers, 2000; this value was refined for every sample); FI, fit index, increases with decreasing quality of the fit; se, mathematical se values of the refinement (2σ level). The error of the EXAFS approach as such is higher; this is revealed by the differences between samples of the same type. Asterisks indicate values that were constrained to be identical for these contributions. Deviations from this simplification do not improve the model significantly.

Sample	No., Type of Ligands per Shell ± se	Distance ± se	2σi2 ± 2σ sd	EF ± se	FI (No. of Variables)
		Å	Å2
Cu-glutathionea	3.6 ± 0.2, S	2.260 ± 0.002	0.006 ± 0.001	−11.5 ± 0.4	0.142
	4.5 ± 0.6, Cu	2.710 ± 0.005	0.021 ± 0.002
Cu(II)-His	5.0 ± 0.8, Nb	2.000 ± 0.006*	0.008 ± 0.001*	−10.5 ± 0.6	0.403
	0.4 ± 0.8, O	2.000 ± 0.006*	0.008 ± 0.001*
Cu(II)-NA, pH 4	3.8 ± 0.3, N/O	1.980 ± 0.003	0.009 ± 0.001	−9.8 ± 0.4	0.251
	3.7 ± 0.8, C	2.862 ± 0.012	0.011 ± 0.004*
	5.0 ± 1.3, C	3.403 ± 0.015	0.011 ± 0.004*
Cu(II)-NA, pH 7	5.6 ± 0.3, N/O	1.975 ± 0.003	0.006 ± 0.001	−9.4 ± 0.5	0.305
	4.1 ± 0.8, C	2.837 ± 0.010	0.006 ± 0.003*
	4.7 ±1.2, C	3.394 ± 0.014	0.006 ± 0.003*
Cu(II)-Pro, pH 7	5.2 ± 0.3, N/O	1.957 ± 0.004	0.008 ± 0.001	−12.5 ± 0.5	0.285

^aMixture of Cu(I) and Cu(II) as obtained by the preparation method.

^bBound to His.