Mitochondria-Directed Fluorescent Probe for the Detection
of Hydrogen Peroxide near Mitochondrial DNA
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Abstract
It
is important to detect hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) near mitochondrial DNA (mtDNA) because mtDNA is more prone
to oxidative attack than nuclear DNA (nDNA). In this study, a mitochondria-targeted
fluorescence probe, <b>pep3-NP1</b>, has been designed and synthesized.
The probe contains a DNA-binding peptide, a H<sub>2</sub>O<sub>2</sub> fluorescence reporter, and a positively charged red emissive styryl
dye to facilitate accumulation in mitochondria. Due to groove binding
of the peptide with DNA, the styryl dye of <b>pep3-NP1</b> intercalated
into the bases of DNA, leading to an increase in red fluorescence
intensity (centered at 646 nm) and quantum yield. In this case, <b>pep3-NP1</b> was a turn-on probe for labeling DNA. Subcellular
locations of <b>pep3-NP1</b> and MitoTracker suggested that <b>pep3-NP1</b> mostly accumulated in the mitochondria of live cells.
Namely, as an intracellular DNA marker, <b>pep3-NP1</b> bound
to mtDNA. In the presence of H<sub>2</sub>O<sub>2</sub>, <b>pep3-NP1</b> emitted green fluorescence (centered at 555 nm). Thus, the ratio
of green with red fluorescence of <b>pep3-NP1</b> was suitable
to reflect the change of the H<sub>2</sub>O<sub>2</sub> level near
mtDNA in living cells. The detecting limit for H<sub>2</sub>O<sub>2</sub> was estimated at 2.9 and 5.0 μM in vitro and in cultured
cells, respectively. The development of <b>pep3-NP1</b> could
help in studies to protect mtDNA from oxidative stress
