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Type: Journal article
Title: X-ray absorption and EPR spectroscopic studies of the biotransformations of chromium(VI) in mammalian cells. Is chromodulin an artifact of isolation methods?
Author: Levina, A.
Harris, H.
Lay, P.
Citation: Journal of the American Chemical Society, 2007; 129(5):1065-1075
Publisher: Amer Chemical Soc
Issue Date: 2007
ISSN: 0002-7863
Statement of
Aviva Levina, Hugh H. Harris, and Peter A. Lay
Abstract: Very different biological activities are usually ascribed to Cr(VI) (a toxin and carcinogen) and Cr(III) (an antidiabetic agent), although recent evidence suggests that both these types of actions are likely to arise from cellular uptake of varying concentrations of Cr(VI). The first systematic study of XANES spectra of Cr(III) complexes formed in Cr(VI)-treated mammalian cells (A549, HepG2, V79, and C2C12 cell lines), and in subcellular fractions of A549 cells, has been performed using a library of XANES spectra of model Cr(III) complexes. The results of multiple linear regression analyses of XANES spectra, in combination with multiple-scattering fits of XAFS spectra, indicate that Cr(III) formed in Cr(VI)-treated cells is most likely to bind to carboxylato, amine, and imidazole residues of amino acids, and to a lesser extent to hydroxo or aqua ligands. A combination of XANES and EPR spectroscopic data for Cr(VI)-treated cells indicates that the main component of Cr(III) formed in such cells is bound to high-molecular-mass ligands (>30 kDa, probably proteins), but significant redistribution of Cr(III) occurs during the cell lysis, which leads to the formation of a low-molecular-mass (<30 kDa) Cr(III)-containing fraction. The spectroscopic (XANES, XAFS, and EPR) properties of this fraction were strikingly similar to those of the purported natural Cr(III)-containing factor, chromodulin, that was reported to be isolated from the reaction of Cr(VI) with liver. These data support the hypothesis that a chromodulin-like species, which is formed from such a reaction, is an artifact of the reported isolation procedure.
Keywords: Liver
Cell Line, Tumor
Carrier Proteins
Carcinogens, Environmental
Electron Spin Resonance Spectroscopy
Spectrometry, X-Ray Emission
Linear Models
Molecular Conformation
Molecular Weight
Models, Biological
Provenance: An erratum for this article has been published. Please click on the link below to view.
Rights: Copyright © 2007 American Chemical Society
DOI: 10.1021/ja063792r
Published version:
Appears in Collections:Aurora harvest
Chemistry and Physics publications
Environment Institute publications

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