A mouse with the ability to mop up free radicals at the cellular level – and live longer as a result – has been created by scientists at the University of Washington.

The research is a boost for the free radical theory of ageing.

The transgenic mice created produce higher-than-normal levels of the antioxidant enzyme catalase. Cells use catalase to convert damaging hydrogen peroxide to harmless water and molecular oxygen, but the enzyme is usually found only in the cytoplasm of cells.

The team made mice that produce high levels of catalase in their mitochondria. They found that cellular damage, as well as age-related damage in the heart, decreased in comparison to control mice that produced catalase in just cytoplasm or in cell nuclei. The lifespan of the mitochondria-catalase mice was extended by more than five months – an increase of around 20%.