Web Date: July 24, 2008
Visualizing Hydrogen Peroxide
A new small-molecule fluorescent probe developed by researchers at the University of California, Berkeley, makes it possible to image hydrogen peroxide specifically in mitochondria of living cells (J. Am. Chem. Soc., DOI: 10.1021/ja802355u).
Mitochondrial H2O2 has been linked to aging, cancer, and neurodegenerative diseases such as Parkinson's, and the ability to track the compound in mitochondria is important to understanding its roles in these conditions. But there has been no simple way to image mitochondrial H2O2 and distinguish it from other reactive oxygen species, such as superoxide, nitric oxide, and hydroxyl radicals.
UC Berkeley assistant professor of chemistry Christopher J. Chang and graduate student Bryan C. Dickinson have developed a probe that can do both. H2O2 reacts with the probe to remove the probe's boronate group and release fluorescent dye.
The probe is based on fluorescent boronate compounds previously developed by Chang's group. But the earlier compounds were not specific to organelles.
Now, Chang and Dickinson have added a mitochondria-targeting phosphonium group to a fluorescent boronate compound. The new fluorophore, called MitoPY1 (shown, Ph = phenyl), fluoresces to indicate rising levels of H2O2 within mitochondria of mammalian cells under stress.
Chang says the synthetic strategy to attach the targeting group can be easily adapted to create probes that target other organelles as well. "The flexibility of our approach is that virtually any functional group can be added in the last step of the synthesis," Chang says.
This probe should help researchers better understand H2O2 production in cells, a goal that has been hampered by a lack of tools, says Michael P. Murphy, a mitochondria expert at the MRC Dunn Human Nutrition Unit, in Cambridge, England.
Leslie B. Poole, a biochemistry professor at Wake Forest University School of Medicine, in Winston-Salem, N.C., says the probe may help demonstrate which mechanisms trigger, regulate, or inhibit mitochondrial H2O2 generation and could also shed light on other H2O2-linked cellular phenomena, such as redox signaling and programmed cell death.
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