Tullius T D, Frank P, Hodgson K O
Department of Chemistry, Stanford University, Stanford, California 94305.
Proc Natl Acad Sci U S A. 1978 Sep;75(9):4069-73. doi: 10.1073/pnas.75.9.4069.
The primary coordination environment of the "blue" copper ion in oxidized azurin has been elucidated by x-ray absorption spectroscopy. The most striking feature is the unambiguous presence of a very short copper-sulfur distance at 2.10 +/- 0.02 A. Nitrogen ligands, presumed to be from imidazoles, are found at 1.97 A. There is some evidence that the copper coordination sphere may be completed by a second sulfur, the distance of which is determined with much less certainty.