Issue 11, 2013

Contrasting Cu, Fe, and Zn isotopic patterns in organs and body fluids of mice and sheep, with emphasis on cellular fractionation

Abstract

We report Cu, Fe, and Zn natural isotope compositions in organs, body fluids, diets and feces of mice and sheep. Large and systematic isotope variability is observed, notably in the δ66Zn in liver and δ65Cu in kidneys, but significant differences exist between mice, sheep and humans, especially in the δ66Zn value of blood. The results are interpreted with reference to current knowledge of metal trafficking and redox conditions in cells. In general, the light isotopes preferentially fractionate into ‘softer’ bonds involving sulfur such as cysteine and glutathione, whereas heavy isotopes fractionate into ‘harder’ bonds involving nitrogen (histidine) and even more oxygen, notably hydroxides, phosphates, and carbonates. Bonds involving the reduced forms Cu+ and Fe2+ are enriched in the light isotopes relative to bonds involving the oxidized Cu2+ and Fe3+ forms. Differences in blood Zn isotope abundances between mice, sheep and humans may reflect a different prevalence of Zn ZIP transporters. The isotopically heavy Cu in the kidneys may reflect isotope fractionation during redox processes and may be relevant to ascorbate degradation into oxalate.

Graphical abstract: Contrasting Cu, Fe, and Zn isotopic patterns in organs and body fluids of mice and sheep, with emphasis on cellular fractionation

Article information

Article type
Paper
Submitted
21 May 2013
Accepted
30 Jul 2013
First published
01 Aug 2013

Metallomics, 2013,5, 1470-1482

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