@article {Funk2004,
	title = {X-ray magnetic circular dichroism of Pseudomonas aeruginosa nickel(II) azurin.},
	journal = {J. Am. Chem. Soc.},
	volume = {126},
	number = {18},
	year = {2004},
	pages = {5859{\textendash}66},
	abstract = {We show that X-ray magnetic circular dichroism (XMCD) can be employed to probe the oxidation states and other electronic structural features of nickel active sites in proteins. As a calibration standard, we have measured XMCD and X-ray absorption (XAS) spectra for the nickel(II) derivative of Pseudomonas aeruginosa azurin (NiAz). Our analysis of these spectra confirms that the electronic ground state of NiAz is high-spin (S = 1); we also find that the L(3)-centroid energy is 853.1(1) eV, the branching ratio is 0.722(4), and the magnetic moment is 1.9(4) mu(B). Density functional theory (DFT) calculations on model NiAz structures establish that orbitals 3d(x2-y2) and 3d(z2) are the two valence holes in the high-spin Ni(II) ground state, and in accord with the experimentally determined orbital magnetic moment, the DFT results also demonstrate that both holes are highly delocalized, with 3d(x2-y2) having much greater ligand character.},
	keywords = {Azurin, Azurin: chemistry, circular dichroism, Circular Dichroism: methods, copper, Copper: chemistry, CRYSTALLOGRAPHY, LIGANDS, Magnetics, models, MOLECULAR, Molecular Conformation, NICKEL, Nickel: chemistry, PDF, Pseudomonas aeruginosa, Pseudomonas aeruginosa: chemistry, X-RAY, X-Rays},
	issn = {0002-7863},
	doi = {10.1021/ja036218d},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/15125678},
	author = {Funk, Tobias and Kennepohl, Pierre and Di Bilio, Angel J and Wehbi, William a and Young, Anthony T and Friedrich, Stephan and Arenholz, Elke and Gray, Harry B and Cramer, Stephen P}
}
