Reduced Energy Conservation During Ageing-Role For Mitochondrial Enzyme

Metabolism sustains life. Aerobic metabolism is the most important type since it generates most of the energy needed. While energy is being produced and conserved, there is also a darker side to aerobic metabolism. It generates free radicals which highly reactive chemical species. These free radicals are capable of damaging membrane structures and molecules. Free radicals have been implicated in the development of a number of chronic diseases like heart disease, diabetes and cancer. Free radical generation leads to the acceleration of ageing.

The generation of free radicals leads to a situation called oxidative stress. To counter oxidative stress, the human body possesses natural defense mechanisms to fight these free radicals. This is called anti oxidative defense and can be brought about by small molecules as well as by enzymes. The best example for an anti oxidative enzyme is superoxide dismutase. In addition, another anti oxidative enzyme has been discovered and has been called Lon protease.

Proteases are enzymes capable of acting on proteins and breaking them down into amino acids, the building blocks for proteins. Thus, Lon protease is an enzyme capable of acting on proteins which become defective and non functional on account of being oxidized by free radicals. Lon protease is a mitochondrial enzyme and protects the mitochondria. It is an established fact that the mitochondria have decreased ability to conserve energy as people age. This is also supported by the fact that the Lon protease levels decline as you age.

Aconitase is an enzyme in the pathway of the tricarboxylic acid cycle (TCA cycle). This enzyme is highly sensitive to oxidation by free radicals. The oxidized form of aconitase is non functional and is removed by the action of Lon protease. But, as you age, Lon protease levels decline and therefore, oxidized form of aconitase accumulates within the mitochondria seriously affecting energy conservation. Thus, one of the reasons for reduced energy conservation during ageing is a drastic fall in the levels of Lon protease.