Mitochondrial. A Critical Role in Aging
Golden TR., Morten K., Johnson F., Samper E., Melov S.
This chapter focuses on research aimed at detecting age-related increases in oxidative damage to protein or lipid components of the mitochondrion. Aging has been associated with both an increase in oxidative damage to proteins and a decrease in protein turnover and repair. The age-related increase in protein modifications includes cross-linkages, fragmentation, carbonylation, glycation, and advanced glycation end-product formation. Several research support mitochondria as the primary source of reactive oxygen species (ROS). Hence, mitochondrial proteins-including the complexes of the electron transport chain and members of other metabolic pathways-are likely to be particularly susceptible to modifications as a result of oxidative damage. Certain cellular components are known to be sensitive to oxidative stress. Specifically, proteins containing iron-sulfur clusters (Fe-S proteins) are highly sensitive to superoxide. Polyunsaturated fatty acids of membrane lipids are susceptible to peroxidation by ROS. The lipid peroxides (lipid-OOH) formed can decompose in the presence of transition metals such as iron to give alkoxy (lipid-O) radicals. These lipid radicals may alter membrane fluidity and subsequently affect the activity of membrane-bound proteins and membrane permeability, ultimately leading to cell degeneration. © 2005 Elsevier Inc. All rights reserved.