Solution Structure of Physiological Cu(His)2: Novel Considerations into Imidazole Coordination

A disagreement on the mode of histidine binding to copper and the structure of [Cu2+(His)2] in solution still exists. Spectroscopic data in solution support a six-coordinate species with N4O2 donor atoms, while X-ray crystallography reveals five-coordinate N3O2 donor atoms. We modified [Cu2+(His)2]...

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Bibliographic Details
Published in:Inorganic chemistry 2009-08, Vol.48 (15), p.7000-7002
Main Authors: Ginotra, Yamini P, Kulkarni, Prasad P
Format: Article
Language:English
Subjects:
Crystallography, X-Ray
Diethyl Pyrocarbonate - chemistry
Histidine - chemistry
Histidine - physiology
Imidazoles - chemistry
Mass Spectrometry
Molecular Structure
Organometallic Compounds - chemistry
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Summary:A disagreement on the mode of histidine binding to copper and the structure of [Cu2+(His)2] in solution still exists. Spectroscopic data in solution support a six-coordinate species with N4O2 donor atoms, while X-ray crystallography reveals five-coordinate N3O2 donor atoms. We modified [Cu2+(His)2] in solution using diethyl pyrocarbonate (DEPC) and monitored the products spectrophotometrically and by mass spectrometry. Our spectrophotometric study indicates the presence of a free imidazole in the [Cu2+(His)2] complex in solution. Mass spectral characterization of a DEPC-modified [Cu2+(His)2] complex yielded a peak at 587.8 amu corresponding to three DEPC adducts. Taken together, our data indicate that the [Cu2+(His)2] complex in solution exists as a neutral five-coordinate structure with N3O2 donor atoms.
ISSN:0020-1669
1520-510X
DOI:10.1021/ic9010983