Chemistry

Manganese Sightings

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Science  17 Sep 2010:
Vol. 329, Issue 5998, pp. 1442
DOI: 10.1126/science.329.5998.1442-c

The biological role of manganese is not limited to its presence in enzymes. In cells, Mn2+ ions that are weakly bound to water, phosphates, carboxylates, or other ligands may combat oxidative stress by reacting with species such as superoxide—or, if present in sufficient concentration, they can also be toxic. The nature of Mn2+ ligand speciation may underlie the varying abilities of different cell types to resist oxidative stress, but the rapid interchange of ligands necessitates in situ methods to study their effect in cells. McNaughton et al. have now shown that a magnetic resonance technique, proton and phosphorus-31 pulsed electron-nuclear double resonance, can be used to assess intracellular phosphate coordination to the paramagnetic manganese ions. The study revealed that the oxidative-stress resistance of mutants of Baker's yeast (Saccharomyces cerevisiae) correlated with the concentration of orthophosphate complexes, which in vitro studies have shown to exhibit superoxide dismutase activity. Having determined average speciation across the entire cell, the authors next plan to probe variations in intact isolated organelles.

Proc. Natl. Acad. Sci. U.S.A. 107, 15335 (2010).

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