Biosensor Measures Oxidative Stress in Living Cells

A highly sensitive biologic measuring system has been developed for determining the oxidation state of living cells in real time.

Cancer, nervous system disorders such as Parkinson's disease, cardiovascular disorders, and old age have one thing in common: both in afflicted tissue and in aging cells, scientists have observed oxidative changes in important biomolecules. These are caused by reactive oxygen molecules, including "free radicals” that are formed as a by-product of cellular respiration and attack cellular proteins, nucleic and fatty acids.

Reactive oxygen molecules are also involved in regulating major life processes such as growth and cell death. The right balance between oxidation and the reverse reaction, reduction, makes the difference between health and disease. "Oxidative stress” arises when this balance shifts towards oxidation-promoting processes.

The biosensor, developed by scientists from the German Cancer Research Center (Heidelberg, Germany), specifically measures the oxidation state of glutathione. This is an important protection molecule that captures a large portion of reactive oxygen molecules within a cell by oxidation. If much of a cell's glutathione is present in an oxidized state, this is an important indicator of the cell's overall oxidation level. The investigators equipped test cells with a fluorescent protein that reacts to changes in oxidation level by releasing light signals. Since the fluorescent protein on its own is not sensitive enough, it was coupled with an enzyme called glutaredoxin. This enzyme "measures” the oxidation state of glutathione and transmits the value to the fluorescent protein.

The stress biosensor measured the slightest changes in the oxidation state of glutathione without destroying the cell. Even more relevant, however, is its precise time resolution, as Dr. Tobias Dick, who helped developed the biosensor, explained, "In order to measure short-term variations of oxidation state, the systems need to react instantly and dynamically. This is guaranteed with our biosensor, which works down to the scale of seconds.”


Related Links:
German Cancer Research Center